The Great Epic of the Bhārata dynasty 12.202.1

12.202.1

yudhiṣṭhira uvāca |
pitāmaha mahāprājña yudhi satyaparākrama |
śrotumicchāmi kārtsnyena kṛṣṇamavyayamīśvaram || 1 ||

"Yudhishthira said, 'O grandsire, O thou of great wisdom and invincible prowess in battle, I wish to hear in detail of Krishna who is immutable and omnipotent. O bull among men, tell me truly everything about his great energy and the great feats achieved by him in days of old. Why did that puissant one assume the form of an animal, and for achieving what particular act? Tell me all this, O mighty warrior!'