Once there lived the best among all sage-poets ever appeared, the most accomplished sublime sage, an embodiment of 'Tapa' (means always engaged in contemplating on the Absolute, like divine sage Nārada) and Svādhyāya (means study and teaching of Vedas; and also rememberance of divine, Japa etc), and an expert in guru-disciple relationship. He had an Āṡrama on the bank of river Tamasā, which was also near to the Gangā river. With the power of chanting ‘Rāma’ Naam, He had become equal to Brahm. He was so great that he was visited by great divinities like Lord Brahmā and celestial sage Nārada on their own. That divine sage was none other than sage Vālmīki.
One day sage Vālmīki was thinking is there such a Sarva-guṇa-sampann Puruṣa (all merited personality, composite in form) completely absolute-like (means second to none) in his qualities, virtues and beauty in the world?! While he was thinking over this, then divine sage Nārada appeared before him who was sent by Lord Brahmā himself, Sage Nārada visits all the worlds and he is a knower of divine secrets. Therefore, sage Vālmīki enquired with divine sage Nārada about such a Sarva-Guna-Sampann Puruṣa with 16 attributes in his Rupa (form, beauty), Guna (qualities and virtues), and Charitra (character) in his 16 questions, He wished to know about such a personality with 16 attributes (qualities) i.e. the Shodash Kalā-Purusha. Here the 'Athāto Brahmā jijñāsā' started, the eqnuiry about the supreme absolute truth who is called Shodash-Kalā- Purusha in Upanishads, and therefore Śrī Rāma is also renowned as Śrī Rāmachandra as his countenance is pleasing to all like the full-moon is to everyone. Although Bhagavan has infinite qualities, in the beginning he manifested the sixteen primary principles for material-creation (11 Indriyas + 5 primordial elements), therefore he is called Shodash Kalā-Purusha.
Then, the divine sage Nārada, knower of everything happening in all the worlds, thought for a while in his heart and said to him “You have asked many rare and unattainable qualities to be found simultaneously in a Person, Yet there is indeed one personality with all these rare qualities You have asked for. That personality is known to others by the name ‘Rāma’ (रामो नाम जनैः श्रुतः). ”
(Sage Vālmīki and sage Nārada both were aware of Shri Rāma, Yet this inquiry (Brahmā jijñāsā) and answering about the Brahman as the Shodash-Kala-Purusha was for the benefit of all the worlds, from Devas to human-beings and all others.)
And thereafter Divine Sage Nārada narrated in brief the life-story of Shri Rāma happened so far.
A while after the departure of Nārada to heavens, Sage Vālmīki along with his dear disciple Bharadwāja went to the riverbanks of Tamasā to perform Sandhyā. Tamasā had very lovely, pleasing, placid and clear waters, and there was a very serene beautiful big and wide forest on its bank, seeing which already delighted Vālmīki strolled around that big and wide beautiful forest, enjoying every part of it.
Vālmīki, then, saw a pair of Krouncha birds chirping melodiously and flying around together in love as if they are one. As he was watching them, a hunter, the nemesis of the birds, shot down the male of the pair. The female of the pair of Krouncha birds, with red colored head and beautiful wings, still under the hangover of deep love that she was enjoying only a moment ago, started crying pitifully, separated from her beloved friend, companion and husband, that male-Krouncha bird lied in a pool of its blood on the ground after thus being shot. She is now separated from him, and gone is that togetherness, she is bewailing for him who had always a heart for her.
Seeing the pitiful wailing of the female Krounchi-bird, after male-bird was shot by hunter, compassion aroused in the heart of Bhagavān Vālmīki. His heart was filled and haunted with compassion, and spontaneously the first verse of the human origin sprung out from the mouth of Bhagavān Vālmīki in anguish and full of compassion for that female-bird. His heart was stirred for her loss and grief.
Yet, the verse which came out spontaneously from his heart in compassion and pathos, made him think about the words again and again, it had come out of his mouth upon being moved by the deep compassion towards the birds. The wise sage brooded over the verse, and said to his disciple Bharadwaja there 'What I have just uttered spontaneously upon being overtaken by grief has four symmetrical quarters in it (each having 8 syllables) and there is certain musical quality to it. This is none other than a Shloka (verse).'
When Sage Vālmīki said thus to his disciple, his disciple Bharadwaja reverently recorded in his mind those unique and unparalleled words with elation, making his Guru happy.
This first-ever Shloka of human-origin spontaneously sprung from Valimiki's mouth was in the most beautiful Anushtup Chhand (meter) in which whole Vālmīki Rāmāyaṇa is composed primarily, Anushtup meter is also the Chanda (poetic meter) of the Purusha-Sukta of Vedas, which also signifies Shri Rāma is the original Purusha of the Purusha-Sukta, and Vālmīki Rāmāyaṇa was composed to expound the deep imports of Vedas. There are 16 letters in each line of the shloka, which tells Shri Rāma is the original Shodash(16)-Kala-Purusha.
People may think how could a sage established in Brahm-jnana be overtaken by a grief of a simple bird?
A divine sage who is established in Brahman, who knows the divine meanings of Vedas completely, and who could feel the love (in union and separation), grief and pity, he was the best suitable personality to experience and feel the love of Sītā and Rāma from deep heart, to compose Rāmāyaṇa, the first ever book of the divine love-story and the life-story of Sītā and Rāma. Thus, Vālmīki was the best sage-poet chosen by Bhagavān to illumine the exploits and the love in union and separation of Sītā and Rāma, the complete biography of supreme how they love, move, talk, laugh, behave and everything else.
Moreover, It is the characteristic of a real Vaishnava, a Vaishnava is full of kindness and compassion inherited from his sweet Lord, his heart melts and can feel the grief and suffering of others.
The 1st shloka of Human-origin with its unique and unparalleled words:
मा निषाद प्रतिष्ठाम्त्व (8) । मगमः शाश्वतीः समाः (8) ।
यत् क्रौङ्च मिथुनात् एक (8) । मवधीः काम मोहितम् (8) ॥
(श्री वाल्मीकि रामायण १.२.१५)
mā niṣāda pratiṣṭhāmtva (8) । magamaḥ śāśvatīḥ samāḥ (8) ।
yat krauṅca mithunāt ēka (8) । mavadhīḥ kāma mōhitam (8) ॥
(Śrī Vālmīki Rāmāyaṇa 1.2.15)
Although overtaken by grief, Vālmīki wished to say (mean) “Oh wretched hunter ! You will not live for many long years, having killed one of the birds that were making deep love to each other.”
Yet, upon deep thought, the verse uttered was an auspicious wish invocation for Shri Rāma that “Oh' Rāma ! As You have eradicated the vice (the lusty demon Ravana), for that You get an everlasting fame and glory in the world till eternity.”
This very unique divine Shloka is the most celebrated Sanskrit-Stanza and bears the layers of divine meanings, It is the seed which carries the stories of each of the seven (7) Kandas of Vālmīki Rāmāyaṇa. Killing of Ravana is the story of 6th Kanda, and thereafter Mandodari (Krounchi) bewailing for her husband. In the Uttar-Kanda i.e. seventh Kanda, Sītā (female-bird) weeps alone in forest due to loss of (separation from) her beloved husband Shri Rāma (male-bird). And so on, all the seven Kandas are secretly present in this particular shloka which originated on its own from the mouth of Sage Vālmīki.
After this Sage Vālmīki taken bath in the river and returned to his Ashram thinking over the meaning of the verse again and again in his mind. When Vālmīki was immersed in thinking the meaning of the shloka he uttered spontaneously, the four-faced Lord Brahmā who commands world came to see the greatest of the Munis sage Vālmīki. Sage Vālmīki welcomed and given him seat and uninterruptedly worshiped Lord Brahmā there. Though, Lord Brahmā himself was before him, yet the mind of sage was elsewhere, still occupied by the grief of the Krounchi bird and the past incident - the killing of Krouncha-bird by the hunter, and he was still brooding over the meaning of that shloka (verse) again and again.
Seeing this, Lord Brahmā said to Sage Vālmīki “Oh, the best of Rishis (Sages) ! Those great words came out from Your mouth at my behest. And You would write the story of Rāma in its entirety.”
धर्मात्मनो भगवतो लोके रामस्य धीमतः ॥
वृत्तम् कथय धीरस्य यथा ते नारदात् श्रुतम् ।
रहस्यम् च प्रकाशम् च यद् वृत्तम् तस्य धीमतः ॥
(श्री वाल्मीकि रामायण १.२.३२-३३)
dharmātmanō bhagavatō lōkē rāmasya dhīmataḥ ॥
vṛttam kathaya dhīrasya yathā tē nāradāt śrutam ।
rahasyam ca prakāśam ca yad vṛttam tasya dhīmataḥ ॥
(Śrī Vālmīki Rāmāyaṇa 1.2.32-33)
Brahmā tells Vālmīki: “O' sage, You shall narrate the legend of Śrī Rāma, the virtuous, intellectual and an intrepid one, in the world he is Bhagavān himself (bhagavatō lōkē : in world, the supreme personality himself, not some ordinary mortal), as you have heard it from sage Nārada. Of that supemely wise Śrī Rāma, every secret revealed or un-revealed so far, will be known to you.”
Brahmā tells Vālmīki “Not a grain of untruth would be there in your composition (न ते वागनृता काव्ये काचिदत्र भविष्यति ). Please write the sacred and wonderful life-story of Rāma set in Shlokas. The entire story of Shri Rāma, Lakshmaṇa, Sītā and all the Rakshasas that is known to others and that is not known to anyone will all be known by you henceforth.”
After requesting this, Lord Brahmā, disappeared.
Then, all the disciples recited again and again that unparalleled unique shloka sprung from the mouth of Valmiki, and all became delighted. That shloka bears the story of Rāma, that is why Lord Brahmā said “the Shloka appeared on my behest, You should write the life-story of Bhagavān Śrī Rāma.”
Sage Valmiki contemplated that he would compose entire Rāmāyaṇa in the same meter, and thereafter he went into deep Yogic-Samadhi and then everything of the life-story of Rāma, the delighter of all in all worlds, known and not known to anyone, was revealed to him in Yogic-Samadhi.
The most enchanting love-story of Sītā and Rāma was revealed to the best of Rishis, Sage Valmiki in his deep Yogic-Samadhi Avastha.
Thus, Vedāvatār Śrī Vālmīki Rāmāyaṇa is not just a history of an ideal hero Rāma or the god in human-form, in fact it is the story of the supreme personality of Godhead himself who has an eternal form like human, who is an adobe of all auspicious qualities, for whom even Brahma himself came to request sage Valmiki to compose his life-story in beautiful melodious verses. Again, a sage like Vālmīki who was always immersed in Brahman had no need to write the life events and biography of an ideal prince, no matter How much great and virtuous that prince was! In reality, sage Vālmīki composed the Rāmāyaṇa primarily to describe the nature, character, disposition, valor, heroism, mercy, compassion, beauty, love, affection, and everything else of the supreme personality of godhead renowned by the name Rāma, and to reinforce the true import of Vedas.
This Upanishad is listed at 54th number in the list of Upanishads given in Muktika-Upanishad. Muktika-Upanishad is quoted by ancient Acharya.
Upanishad starts with Shanti Mantra
सनकाद्या योगिवर्या अन्ये च ऋषयस्तथा ।
प्रह्लादाद्या विष्णुभक्ता हनूमन्तमथाब्रुवन् ॥ १॥
“[Once] the exalted Yogis and sages Sanaka, Mudgala, Shāndilya, Paingala etc., and Prahlāda and other great devotees of Lord Vishṇu [approached and] spoke to Lord Hanumān —
वायुपुत्र महाबाहो किंतत्त्वं ब्रह्मवादिनाम् ।
पुराणेष्वष्टादशसु स्मृतिष्वष्टादशस्वपि ॥ २॥
चतुर्वेदेषु शास्त्रेषु विद्यास्वाध्यात्मिकेऽपि च ।
सर्वेषु विद्यादानेषु विघ्नसूर्येशशक्तिषु ॥ ३॥
एतेषु मध्ये किं तत्त्वं कथय त्वं महाबल ॥ ४॥
vāyuputra mahābāhō kiṃtattvaṃ brahmavādinām ।
purāṇēṣvaṣṭādaśasu smṛtiṣvaṣṭādaśasvapi ॥ 2॥
caturvēdēṣu śāstrēṣu vidyāsvādhyātmikē'pi ca ।
sarvēṣu vidyādānēṣu vighnasūryēśaśaktiṣu ॥ 3॥
ētēṣu madhyē kiṃ tattvaṃ kathaya tvaṃ mahābala ॥ 4॥
O' Vayu-Putra (the son of wind-god), the mighty armed one! What is the supreme essence (tattva) realised by Brahmvadis (who speaks on the supreme Absolute truth, Brahm)? What is to be recognised as the supreme essence (tattva) among all knowledge and philosophy propounded in the eighteen (18) Purāṇas, and also in the eighteen (18) Smritis, in the four Vedas, in the Shastras, and also in the Adhyātma-Vidyās related to realization of ātmā (soul and super-soul), and in the Vidyās (knowledge, doctrines) related to Gāṇpatya, Saura, Shāktas, [Shaiva, and Vaishnava] schools of thoughts? Please tell us, O' great mighty one!”
Then Hanumān said to them —
भो योगीन्द्राश्चैव ऋषयो विष्णुभक्तास्तथैव च ।
श्रुणुध्वं मामकीं वाचं भवबन्धविनाशिनीम् ॥४॥
एतेषु चैव सर्वेषु तत्त्वं च ब्रह्म तारकम् ।
राम एव परं ब्रह्म तत्त्वं श्रीरामो ब्रह्म तारकम् ॥५॥
bhō yōgīndrāścaiva ṛṣayō viṣṇubhaktāstathaiva ca ।
śruṇudhvaṃ māmakīṃ vācaṃ bhavabandhavināśinīm ॥
ētēṣu caiva sarvēṣu tattvaṃ ca brahma tārakam ।
rāma ēva paraṃ brahma tattvaṃ śrīrāmō brahma tārakam ॥
“O' Best among Yogis, great sages, and great Vaishnava devotees, please listen my words carefully which are capable to cut all the bondages of worldly existence; After due investigation in all these (aforementioned texts - four Vedas, eighteen (18) Purāṇas, eighteen (18) Smritis, and various other Shastras, and also in the Shastras with prominence of Ganpati, Surya, Shakta, Shiva and Vishṇu) and infact in all the knowledges and in all the Tattvas, the greatest principle (the supreme essence) is the Brahm-Tārakam, Śrī Rāma alone is Parabrahm (the supreme absolute Brahm), the Param tattva and the Brahm-Tarakam (indicated by Turya-Turiyatit Brahm).”
वायुपुत्रेणोक्तास्ते योगीन्द्रा ऋषयो विष्णुभक्ता
हनूमन्तं पप्रच्छुः — रामस्याङ्गानि नो ब्रूहीति ॥७॥
vāyuputrēṇōktāstē yōgīndrā ṛṣayō viṣṇubhaktā
hanūmantaṃ papracchuḥ — rāmasyāṅgāni nō brūhīti ॥7॥
“When thus spoken to them by Vāyuputra (Hanumān), They all again asked Lord Hanumān — ‘Please tell us the Angas (limbs or parts) of Bhagavān Śrī Rāma.’”
(After knowing about the supreme Tattva Rāma, now those exalted sages and great devotees wanted to know the limbs of Savishesh Brahman aspect of Śrī Rāma, what are his limbs i.e. parts.)
Then, Hanumān said to them —
वायुपुत्रं विघ्नेशं वाणीं दुर्गां
क्षेत्रपालकं सूर्यं चन्द्रं नारायणं नारसिंहं
वासुदेवं वाराहं तत्सर्वान् मन्त्रान् सीतां लक्ष्मणं
शत्रुघ्नं भरतं विभीषणं सुग्रीवमङ्गदं
जाम्बवन्तं प्रणवमेतान् रामस्याङ्गानि जानीथाः ।
vāyuputraṃ vighnēśaṃ vāṇīṃ durgāṃ
kṣētrapālakaṃ sūryaṃ candraṃ nārāyaṇaṃ nārasiṃhaṃ
vāsudēvaṃ vārāhaṃ tatsarvān mantrān sītāṃ lakṣmaṇaṃ
śatrughnaṃ bharataṃ vibhīṣaṇaṃ sugrīvamaṅgadaṃ
jāmbavantaṃ praṇavamētān rāmasyāṅgāni jānīthāḥ ।
(Rāmarahasya Upaniṣad 1.7)
“Know these following deities : Vāyuputra (i.e. myself Hanumān), Vighnēśa (Ganesha), Vāṇī (Dēvī Sarasvati), Dēvī Durgā, Kṣētrapālakas (the guardians of the regions), Sūrya (the sun-god), Chandra (the moon-god), Bhagavān Nārāyaṇa, Lord Nārasiṃha (the man-lion incarnation), Lord Vāsudēva, Lord Vārāha (the divine boar incarnation) and their all divine mantras, and Dēvī Sītā, Lord Lakṣmaṇa, Lord Bharat, Lord Śatrughna, Vibhīṣaṇa, Sugrīva, Aṅgada, Jāmbavanta, Praṇavam (Oṃ) — all these are aṅgas (limbs, parts) of Bhagavān Śrī Rāma.”
Thus, Avatāri and Avatāras, Oṃ (Shabd-Brahm) and divine paraphernalias are the limbs (parts) of Bhagavān Śrī Rāma.
Gosvami Tulsidasa who is the incarnation of sage Vālmīki (- Bhavishyottar Purāṇa), says same thing in Śrī Rāmacharitmānas, that Śrī Rāma is like billions of Lord Vishṇu, infinite billions of Maa Durgā and billions of Lord Shiva.
रामु काम सत कोटि सुभग तन । दुर्गा कोटि अमित अरि मर्दन ॥
सक्र कोटि सत सरिस बिलासा । नभ सत कोटि अमित अवकासा ॥
rāmu kāma sata kōṭi subhaga tana । durgā kōṭi amita ari mardana ॥
sakra kōṭi sata sarisa bilāsā । nabha sata kōṭi amita avakāsā ॥
भावार्थ:-श्री रामजी का अरबों कामदेवों के समान सुंदर शरीर है। वे अनंत कोटि दुर्गाओं के समान शत्रुनाशक हैं। अरबों इंद्रों के समान उनका विलास (ऐश्वर्य) है। अरबों आकाशों के समान उनमें अनंत अवकाश (स्थान) है |
“Śrī Rāma's body possesses the charm of a myriad Cupids. He is as inexorable in crushing the enemy as countless millions of Durgās. He enjoys the luxury of a myriad Indra-s and is immeasurable in expanse as a myriad firmaments.”
सारद कोटि अमित चतुराई । बिधि सत कोटि सृष्टि निपुनाई ॥
बिष्नु कोटि सम पालन कर्ता । रुद्र कोटि सत सम संहर्ता ॥
sārada kōṭi amita caturāī । bidhi sata kōṭi sṛṣṭi nipunāī ॥
biṣnu kōṭi sama pālana kartā । rudra kōṭi sata sama saṃhartā ॥
भावार्थ:- उनमें अनंतकोटि सरस्वतियों के समान चतुरता है। अरबों ब्रह्माओं के समान सृष्टि रचना की निपुणता है। वे करोड़ों विष्णुओं के समान पालन करने वाले और अरबों रुद्रों के समान संहार करने वाले हैं |
“He is as sharp as countless millions of Saraswatis-s and possesses the creative skill of a myriad Brahmā-s. Again, He is as good a preserver as billions of Vishṇu-s and as thorough a destroyer as billions of Rudra-s.”
निरुपम न उपमा आन राम समान रामु निगम कहै ।
जिमि कोटि सत खद्योत सम रबि कहत अति लघुता लहै॥
nirupama na upamā āna rāma samāna rāmu nigama kahai ।
jimi kōṭi sata khadyōta sama rabi kahata ati laghutā lahai॥
भावार्थ:-श्री रामजी उपमारहित हैं, उनकी कोई दूसरी उपमा है ही नहीं। श्री राम के समान श्री राम ही हैं, ऐसा वेद कहते हैं। जैसे अरबों जुगनुओं के समान कहने से सूर्य। (प्रशंसा को नहीं वरन) अत्यंत लघुता को ही प्राप्त होता है (सूर्य की निंदा ही होती है) |
“Incomparable as He is, He has no compeer. Śrī Rāma alone is Śrī Rāma's peer - so declare the Vedas - even as the sun really suffers diminution by being likened to a myriad glow-worms.”
In scriptures, it is told Śrī Rāma shown cosmic universal form to his mother Kaushalya, his devotee Kak-Bhusundi (in Rāmacharitmanas and other Rāmāyaṇa-Samhitas) and Parashurāma (in Mahābhārata).
One day, mother Kausalyå washed and adorned her child Śrī Rāma and put him to sleep in the cradle. Thereafter she taken bath and went to worship the patron deity of her family. Having worshipped the deity she offered Him Naivedya-Bhoga, and then returned to the kitchen. When she came back to the place of worship, she beheld her boy eating the food that was offered to the Lord. Frightened at this, the mother went to her boy and found Him asleep in the nursery. Coming back once more to the temple, she still saw the boy there. She now trembled with fear and her mind found no rest. She saw two Rāma-s, one in the temple and the other in the nursery. She said to herself, “Is it my mental illusion or some other unusual phenomenon?” When Śrī Rāma saw his mother so perplexed, the Lord gently smiled.
देखरावा मातहि निज अद्भुत रूप अखंड।
रोम रोम प्रति लागे कोटि कोटि ब्रह्मंड॥
dēkharāvā mātahi nija adbhuta rūpa akhaṃḍa।
rōma rōma prati lāgē kōṭi kōṭi brahmaṃḍa॥
“The Lord then revealed to his mother his marvellous infinite form, every pore of whose skin contained millions and billions of universes.”
अगनित रबि ससि सिव चतुरानन। बहु गिरि सरित सिंधु महि कानन॥
काल कर्म गुन ग्यान सुभाऊ। सोउ देखा जो सुना न काऊ॥
देखी माया सब बिधि गाढ़ी। अति सभीत जोरें कर ठाढ़ी॥
देखा जीव नचावइ जाही। देखी भगति जो छोरइ ताही॥
aganita rabi sasi siva caturānana। bahu giri sarita siṃdhu mahi kānana॥
kāla karma guna gyāna subhāū। sōu dēkhā jō sunā na kāū॥
dēkhī māyā saba bidhi gāḍha़ī। ati sabhīta jōrēṃ kara ṭhāḍha़ī॥
dēkhā jīva nacāvai jāhī। dēkhī bhagati jō chōrai tāhī॥
“She saw therein countless suns and moons, Shivas and four-faced Brahmās, and a number of mountains, rivers, oceans, plains and woods, as well as the spirit of time, the principle of action, the modes of Prakæti (Sattva, Rajas and Tamas), the spirit of knowledge and Nature and many more things of which she had never heard before. She further beheld Māyā, who is powerful in every respect, yet stricken with terror and standing with her palms joined together to supplicate Lord. The mother also beheld Jiva the embodied soul, who is made to dance by Māyā, and even so Bhakti-devi the spirit of devotion which whi liberates the soul.”
The hair on the mother's body bristled and she stood speechless. Closing her eyes she bowed her head at the Lord's feet. Seeing the mother struck with wonder the Slayer of Khara assumed the form of a child again. She was unable to utter praises and trembled at the thought that she had looked upon the Father of the universe as her own child. Shri Hari comforted His mother in many ways and said, "Listen, My mother: do not reveal this fact anywhere (that You saw my universal form and who am I).
ऋचीकनन्दनो रामो भार्गवो रेणुकासुतः ।
तस्य दाशरथेः श्रुत्वा रामस्याक्लिष्टकर्मणः ॥४२॥
(महाभारत, वनपर्व ९९.४२)
ṛcīkanandanō rāmō bhārgavō rēṇukāsutaḥ ।
tasya dāśarathēḥ śrutvā rāmasyākliṣṭakarmaṇaḥ ॥42॥
(Mahābhārata, vanaparva 99.42)
“Heard of the glory and extraordinary legendary exploits of Śrī Rāma, Once Reṇukānandan Parashurāma borned in the lineage of sage Richika and sage Bhrigu, became very much eager to see Śrī Rāma who is unwearied in action.. ”
Then, Parshurāma came Ayōdhyā with the divine bow (the bow of Visnu) which was used by him to kill many Kshatariyas in past.[Mahābhārata, Van-Parv 99.43]
Parshurāma (an incarnation of Bhagavān Vishṇu) was actually willing to see Bhagavān Śrī Rāma, and He was also desirous to see the extraordinary valour and strength of Bhagavān Śrī Rāma. 
When Mahārāja Dasarath heard Parshurāma has arrived at the border of city Ayōdhyā, then he sent his son Śrī Rāma to welcome sage Parshurāma.
Seeing Śrī Rāma arrived and standing with his bow to welcome him, sage Parshurāma talked with Śrī Rāma in some offensive manner (smilingly) and said this to Shri Rāma “if you have strength and valour, then take aim with an arrow on the bow of Visnu brought by me. This is the bow from which I have eliminated many Kshatriyas.”
(This way I can test your extraordinary strength and valour and then after we can have combative duel.)
Shri Rāma took that divine bow from Parashurāma and effortlessly tighten the string on the bow, and then he smilingly caused a thundering sound from the thread of that divine bow. Hearing that tumultuous frightening sound with lightening, all-beings became fearful. Then Śrī Rāma asked sage Parashurāma what to do next? Then, Sage Parashurāma given an arrow to him to take aim. Śrī Rāma fitted the arrow on the string of the bow.
Then, Śrī Rāma thought to show his real divine nature to Parashurāma, and then after his strength to destroy Parashurāma's pride. Bhagavān Śrī Rāma said to Parashurāma You are very proud of your strength, first see my real nature :
महाभारत, वनपर्व- अध्याय-99 continued..
पश्य मां स्वेन रूपेण चक्षुस्ते वितराम्यहम् ।
ततो रामशरीरे वै रामः पश्यति भार्गवः ॥५६॥
आदित्यान् सवसून् रुद्रान सांध्यांश्च समरुद्गणान् ।
पितरो हुतानशनश्चैव नक्षात्राणि ग्रहास्तथा ॥५७॥
गन्धर्वा राक्षसा यक्षा नद्यस्तीर्थानि यानि च ।
ऋषयो बालखिल्याश्च ब्रह्मभूताः सनातनाः ॥५८॥
देवर्षयश्च कार्त्स्न्येन समुद्राः पर्वतास्तथा ।
वेदाश्च सोपनिषदो वषट्कारैः सहाध्वरैः ॥५९॥
चेतोवन्ति च सामानि धनुर्वेदश्च भारत ।
मेघवृन्दानि वर्षाणि विद्युतश्च युधिष्ठिर ॥६०॥
(महाभारत, वनपर्व ९९.५६-६०)
paśya māṃ svēna rūpēṇa cakṣustē vitarāmyaham ।
tatō rāmaśarīrē vai rāmaḥ paśyati bhārgavaḥ ॥56॥
ādityān savasūn rudrāna sāṃdhyāṃśca samarudgaṇān ।
pitarō hutānaśanaścaiva nakṣātrāṇi grahāstathā ॥57॥
gandharvā rākṣasā yakṣā nadyastīrthāni yāni ca ।
ṛṣayō bālakhilyāśca brahmabhūtāḥ sanātanāḥ ॥58॥
dēvarṣayaśca kārtsnyēna samudrāḥ parvatāstathā ।
vēdāśca sōpaniṣadō vaṣaṭkāraiḥ sahādhvaraiḥ ॥59॥
cētōvanti ca sāmāni dhanurvēdaśca bhārata ।
mēghavṛndāni varṣāṇi vidyutaśca yudhiṣṭhira ॥60॥
(Mahābhārata, Vanaparva 99.56-60)
(Sage Lomasha who was narrating this leela of to Yuddhisthira said to him:)
“Shri Rāma said - ‘O' Parashurāma, I am giving you divine sight through which see me in reality who am I (my real form).’
Then, In the body of Shri Rām with Vishṇu, Parashurāma saw all twelve Aaditya-s, all eleven Rudra-s, all eight Vasu-s, all demi-gods (Sādhya Devtā-s), all fourty nine Maruta-s, Pitar-devas, Agni-Dev, stars, planets, Gandharva-s, Yaksha-s, rivers, all Tirthas, divine sages, Brahmbhuta eternally young Rishi-s, oceans, mountains, all Vedas along with Upanishadas, Saam Veda and Dhanur-Veda, Vashatkar, Yajnas, terrific group of roaring clouds, thunderstorms, and lightnings and everything else ― as if those everything became alive in the body of Shri Rāma, O' Yuddhisthir!” [Mahabharat Van-Parva 99.56-60]
ततः स भगवान्विष्णुस्तं वै बाणं मुमोच ह।
शुष्काशनिसमाकीर्णं महोल्काभिश्च भारत ॥६१॥
पांसुवर्षेण महता मेघवर्षैश्च भूतलम्।
भूमिकम्पैश्च निर्घातैर्नादैश्च विपुलैरपि ॥६२॥
स रामं विह्वलं कृत्वा तेजश्चाक्षिप्य केवलम्।
आगच्छज्ज्वलितो बाणो रामबाहुप्रचोदितः ॥६३॥
(महाभारत, वनपर्व ९९.६१-६३)
tataḥ sa bhagavānviṣṇustaṃ vai bāṇaṃ mumōca ha।
śuṣkāśanisamākīrṇaṃ mahōlkābhiśca bhārata ॥61॥
pāṃsuvarṣēṇa mahatā mēghavarṣaiśca bhūtalam।
bhūmikampaiśca nirghātairnādaiśca vipulairapi ॥62॥
sa rāmaṃ vihvalaṃ kṛtvā tējaścākṣipya kēvalam।
āgacchajjvalitō bāṇō rāmabāhupracōditaḥ ॥63॥
(Mahābhārata, Vanaparva 99.61-63)
Sage Lomasha said to Yuddhisthir -
“O' Bhārat! The Vishṇu[-like] Bhagavān Shri Rāma [Vishṇu means all pervading universal], then fired the arrow by taking aim with that divine bow. Whole world became full of terrific thunderstorms and lightnings in the sky, in spite of absence of clouds in the sky. Frequent shock waves orginated all where and took the form of frequent earthquakes. Sky became full of many types of terrific thunderings and roaring of clouds. That inflamed missile fired from the arms of Śrī Rāma agonized Parashurāma and returned back to Śrī Rām after snatching only the divine (Vaishanvi) spendour of Parashurāma.”
This amazing event is not just the handing over or taking over of the divine bow of Vishṇu, but Shri Rāma secretly took out the Vaishnavi-tejam present in Parashurāma, this shows Shri Rāma is the original personality of godhead, the Brahm himself and the Vishṇu-tattvas are ruled by him.
In Nrisimha Purāna, Parashurāma heard the news the bow of Lord Shiva is broken by Shri Rāma, therefore he appeared suddenly to confront Śrī Rāma when the newly married couples with Maharaj Dasarath and the jubilant marriage party and the army were on the way towards Ayodhya. Seeing angry Parashurāma, Mahārāja Dasarath became very anxious.
युष्माभिरत्र रामार्थं न कार्य दुःखमण्वपि ॥१४२॥
पित्रा वा मातृभिर्वापि अन्यैर्भृत्यजनैरपि ।
अयं हि नृपते रामः साक्षाद्विष्णुस्तु ते गृहे ॥१४३॥
जगतः पालनार्थाय जन्मप्राप्तो न संशयः ।
यस्य संकीर्त्य नामपि भवभीतिः प्रणश्चति ॥१४४॥
ब्रह्म मूर्तं स्वयं यत्र भयादेस्तत्र का कथा ।
(श्रीनरसिंह पुराण ४७.१४२-१४५)
yuṣmābhiratra rāmārthaṃ na kārya duḥkhamaṇvapi ॥142॥
pitrā vā mātṛbhirvāpi anyairbhṛtyajanairapi ।
ayaṃ hi nṛpatē rāmaḥ sākṣādviṣṇustu tē gṛhē ॥143॥
jagataḥ pālanārthāya janmaprāptō na saṃśayaḥ ।
yasya saṃkīrtya nāmapi bhavabhītiḥ praṇaścati ॥144॥
brahma mūrtaṃ svayaṃ yatra bhayādēstatra kā kathā ।
(Śrī Narasiṃha Purāṇa 47.142-145)
Then, sage Vashishtha said to Mahārāja Dasarath -
“O' King! You people, father or mother or other relatives and servants, should not feel sad for Śrī Rāma. This Rāma is in fact (all pervading) Lord Vishṇu himself in Your home. He has appeared for the sake of protecting and maintaining this world, without any doubt. Mere singing whose name destroys all the fears of this world, where the Brahm himself (the supreme absolute himself) is personified, then for what there should be any fear?”
इत्युक्ते भार्गवो रामो राममाहाग्रतः स्थितम् ॥१४६॥
त्यज त्वं रामसंज्ञां तु मया वा संगरं कुरु ।
इत्युक्ते राघवः प्राह भार्गवं तं पथि स्थितम् ॥१४७॥
रामसंज्ञां कुतस्त्यक्ष्ये त्वया योत्स्ये स्थिरो भव ।
इत्युक्त्वा तं पृथक् स्थित्वा रामो राजीवलोचनः ॥१४८॥
ज्याघोषमकरोद्वीरो वीरस्यैवाग्रतस्तदा ।
ततः परशुरामस्य देहान्निष्क्रम्य वैष्णवम् ॥१४९॥
पश्यतां सर्वभूतानां तेजो राममुखेऽविशत् ।
दृष्ट्वा तं भार्गवो रामः प्रसन्नवदनोऽब्रवीत् ॥१५०॥
राम राम महाबाहो रामस्त्वं नात्र संशयः ।
विष्णुरेव भवाञ्जातो ज्ञातोऽस्यद्य मया विभो ॥१५१॥
(श्रीनरसिंह पुराण ४७.१४६-१५१)
ityuktē bhārgavō rāmō rāmamāhāgrataḥ sthitam ॥146॥
tyaja tvaṃ rāma-saṃjñāṃ tu mayā vā saṃgaraṃ kuru ।
ityuktē rāghavaḥ prāha bhārgavaṃ taṃ pathi sthitam ॥147॥
rāma-saṃjñāṃ kutas-tyakṣyē tvayā yōtsyē sthirō bhava ।
ityuktvā taṃ pṛthak sthitvā rāmō rājīvalōcanaḥ ॥148॥
jyā-ghōṣam-akarōd-vīrō vīrasyaivāgratastadā ।
tataḥ paraśurāmasya dēhān-niṣkramya vaiṣṇavam ॥149॥
paśyatāṃ sarva-bhūtānāṃ tējō rāmamukhē'viśat ।
dṛṣṭvā taṃ bhārgavō rāmaḥ prasannavadanō'bravīt ॥150॥
rāma rāma mahābāhō rāmas-tvaṃ nātra saṃśayaḥ ।
viṣṇurēva bhavāñjātō jñātō'syadya mayā vibhō ॥151॥
(Śrī Narasiṃha Purāṇa 47.146-151)
“While Vashishtha was telling these words (in order to remove the sadness and fear gripped to people there), then Parashurāma said to Bhagavān Śrī Rāma who was standing in front of him - ‘O' Rāma, You should either forsake Your name Rāma, or do war with me.’ Being said thus by Bhārgava Parashurāma, Śrī Rāma said to him ‘how can I discard my name Rāma? Let there be war with You, better You be alert now.’ After telling thus to him, the Rājīvalōcana (red-lotus eyed) Śrī Rāma stood little away from him and caused a shaking sound from the tightened bow-string. Then, the divine splendor of Vishṇu came out from the body of Parashurāma and entered in the mouth of Śrī Rāma, while being seen by all-beings there. Then Bhargava-rāma looked towards Śrī Rāma and became delighted [to see his splendor merged into the original divinity] and said - ‘O' Rāma, O' mighty- armed Rāma, You alone are Rāma, there is no doubt in this. Prabhu, I have realised You today, You are Vishṇu himself [the all pervading Brahm himself] who has appeared.”
Parashurāma wanted to know If the supreme tattva renowned by the name Śrī Rāma himself has appeared? When the divine splendor of Vishṇu present in him came out and merged in the divine splendor of the original divinity, seeing Śrī Rāma himself glowing with splendor, Parashurāma realised here is Śrī Rāma himself the supreme Lord.
In Mahabharat, Parashurāma lost his splendor and became unconscious from the arrow released by Śrī Rāma.
स तु विह्वलतां गत्वा प्रतिलभ्य च चेतनाम् ।
रामः प्रत्यागतप्राणः प्राणमद् विष्णुतेजसम् ॥६४॥
विष्णुना सोऽभ्यनुज्ञातो महेन्द्रमगमत् पुनः ।
भीतस्तु तत्र न्यवसद् व्रीडितस्तु महातपाः ॥६५॥
(महाभारत, वनपर्व ९९.६४-६५)
sa tu vihvalatāṃ gatvā pratilabhya ca cētanām ।
rāmaḥ pratyāgataprāṇaḥ prāṇamad viṣṇutējasam ॥64॥
viṣṇunā sō'bhyanujñātō mahēndramagamat punaḥ ।
bhītastu tatra nyavasad vrīḍitastu mahātapāḥ ॥65॥
(Mahābhārata, vanaparva 99.64-65)
“Being excessively agnoized from Lord Rāma's arrow, Parashurāma became unconscious. After sometime he regained his consciousness as like he became alive after death. 
Then Parashurāma made salutation to Śrī Rāma who had taken his Vishṇu-teja. After then taking permission from Shri Rāma the Vishṇu himself, Parashurāma returned back to Mahendra-Parvat from where he had come. Fearful and rendered vigourless, Parashurāma started penance there.” [Mahābhārata Van-Parva 99.65]
In Vālmīki Rāmāyaṇa also, Parashurām was rendered without Vaishnavi-splendour by Lord Śrī Rāma. Before going to Mahendra-Parvat, Parashurāma eulogized Śrī Rāma as the god of gods, the supreme-being.
अक्षय्यम् मधु हन्तारम् जानामि त्वाम् सुरेश्वरम् ।
धनुषो अस्य परामर्शात् स्वस्ति ते अस्तु परंतप ॥
(श्रीवाल्मीकि रामायण १.७६.१७)
akṣayyam madhu hantāram jānāmi tvām surēśvaram ।
dhanuṣō asya parāmarśāt svasti tē astu paraṃtapa ॥
(Śrī Vālmīki Rāmāyaṇa 1.76.17)
Parashurāma said to Śrī Rāma:
“I have realized your touch of nature as that of the Immutable Supreme Being, God of Gods, the Exterminator of the demon Madhu, namely Vishṇu, by the touch of your handling that bow... oh, enemy-inflamer, blessedness alone betides you...”
न च इयम् तव काकुत्स्थ व्रीडा भवितुम् अर्हति ।
त्वया त्रैलोक्य नाथेन यत् अहम् विमुखी कृतः ॥
(श्रीवाल्मीकि रामायण १.७६.१९)
na ca iyam tava kākutstha vrīḍā bhavitum arhati ।
tvayā trailōkya nāthēna yat aham vimukhī kṛtaḥ ॥
(Śrī Vālmīki Rāmāyaṇa 1.76.19)
“Oh, Kakutstha Śrī Rāma, you are the lord of the triad of worlds, such as you are, you faced me down, and Therefore I am not feeling ashamed after being defeated by you.”
राम राम महाबाहो वेदिमत्वंसनातनम् ।
जानाम्यद्यैव काकुत्स्थ तव वीर्यगुणादिभिः ॥
rāma rāma mahābāhō vēdima-tvaṃ-sanātanam ।
jānāmy-adyaiva kākutstha tava vīrya-guṇādibhiḥ ॥
Parashurāma said -
“O' Shri Rāma, O' Shri Rāma, O great armed lord, I realised now your true nature of being eternal god, O Kakutstha Rāma, I have now realised your auspicious qualities and your supreme valour!”
त्वं आदि पुरुषः साक्षात् परमब्रह्म परोऽव्ययः ।
त्वं अनंतो महाविष्णुः वासुदेवः परात्परः ॥
tvaṃ ādi puruṣaḥ sākṣāt paramabrahma parō'vyayaḥ ।
tvaṃ anaṃtō mahāviṣṇuḥ vāsudēvaḥ parātparaḥ ॥
“O' Śrī Rāma, You are the primeval god of universe, You are Parabrahm himself, You are the supreme imperishable element of the cosmos! O' Śrī Rāma, You are infinite (ananta), You are Maha-Vishṇu, You are Parātpar Vāsudeva, You are even higher than the highest!”
There is a long hymb by Bhagavān Parashurāma in revealing the true nature of Bhagavān Śrī Rāma, the original personality of godhead.