Vishnupurana 4.2.17

4.2.17

ūcuś cainaṃ |
bho bhoḥ kṣatriyavaryāsmābhir abhyarthitena bhavatāsmākam arātivadhodyatānāṃ sāhāyyaṃ kṛtam icchāmaḥ |
tad bhavatāsmākam abhyāgatānāṃ praṇayabhaṅgo na kāryaḥ |
ity uktaḥ puraṃjayaḥ prāha |
sakalatrailokyanātho yo 'yaṃ yuṣmākam indraḥ śatakratur asya yady ahaṃ skandhārūḍho yuṣmadarātibhiḥ saha yotsye tadāhaṃ bhavatāṃ sahāyaḥ |
ity ākarṇya samastadevair indreṇa ca bāḍham ity evaṃ samanvicchitam ||

In the Treta age a violent war broke out between the gods and the Asuras, in which the former were vanquished. They consequently had recourse to Vishńu for assistance, and propitiated him by their adorations. The eternal ruler of the universe, Náráyańa, had compassion upon them, and said, "What you desire is known unto me. Hear how your wishes shall be fulfilled. There is an illustrious prince named Puranjaya, the son of a royal sage; into his person I will infuse a portion of myself, and having descended upon earth I will in his person subdue all your enemies. Do you therefore endeavour to secure the aid of Puranjaya for the destruction of your foes." Acknowledging with reverence the kindness of the deity, the immortals quitted his presence, and repaired to Puranjaya, whom they thus addressed: "Most renowned Kshatriya, we have come to thee to solicit thy alliance against our enemies: it will not become thee to disappoint our hopes." The prince replied, "Let this your Indra, the monarch of the spheres, the god of a hundred sacrifices, consent to carry me upon his shoulders, and I will wage battle with your adversaries as your ally." The gods and Indra readily answered, "So be it;" and the latter assuming the shape of a bull, the prince mounted upon his shoulder. Being then filled with delight, and invigorated by the power of the eternal ruler of all movable and immovable things, he destroyed in the battle that ensued all the enemies of the gods; and because he annihilated the demon host whilst seated upon the shoulder (or the hump, Kakud) of the bull, he thence obtained the appellation Kakutstha (seated on the hump).