Mahabharata 1.44.22

1.44.22

bhagavāniva deveśaḥ śūlapāṇirhiraṇyadaḥ |
vivardhamānaḥ sarvāṃstānpannagānabhyaharṣayat || 22 ||

And in due time, the sister of the snakes, O Brahmana, gave birth to a son of the splendour of a celestial child, who became the reliever of the fears of his ancestors and maternal relatives. The child grew up there in the house of the king of the snakes. He studied the Vedas and their branches with the ascetic Chyavana, the son of Bhrigu. And though but a boy, his vows were rigid. And he was gifted with great intelligence, and with the several attributes of virtue, knowledge, freedom from the world's indulgences, and saintliness. And the name by which he was known to the world was Astika. And he was known by the name of Astika (whoever is) because his father had gone to the woods, saying. 'There is', when he was in the womb. Though but a boy, he had great gravity and intelligence. And he was reared with great care in the palace of the snakes. And he was like the illustrious lord of the celestials, Mahadeva of the golden form, the wielder of the trident. And he grew up day by day, the delight of all the snakes.'"