Srimad Bhagvata Mahapurana: Book 10: Chapter 16: Verses 29-37
Continuing to dance (with untiring zeal) Sri Krsna (the most ancient Person) subdued the cobra, successively bending under His foot whichever of the heads of the snake-that was ejecting poison through its eyes and violently hissing in rage-would raise itself. (With His feet bespatterd with the drops of blood ejected from the eyes of the serpent) the Lord appeared as though devoutly worshipped with flowers. With its umbrella-like hoods crushed by the Lord's weird dance and its limbs shattered (due to the expansion of Sri Krsna's body), and spouting copious blood through its mouths, the serpent (now) thought of Lord Narayana, the most ancient Person, the adored of the mobile as well as of the immobile creation, and mentally sought Him as its protector.
Distressed to perceive the snake sinking under the immense weight of Sri Krsna, who holds the (numberless) universes in His abdomen, and its umbrella-like hoods crushed under the strokes of His heels, its wives approached the Lord (the most ancient Person), their clothes and ornaments as well as their hair-bands falling in disorder. Leading their children before them and stretching their body on the ground, those chaste wives (of the serpent) presently bowed low to the aforesaid Sri Krsna (the Protector of all created beings) with joined palms and, eager to secure the deliverance of their sinful husband, sought the Lord, who affords protection to all, as their refuge. The wives of the serpent prayed: Just is the punishment meted out to this offender; for Your descent (on this earth) is intended for chastising the wicked and You regard Your enemy as well as Your sons with an undifferentiating eye.
(Nay,) You inflict punishment (only) because You anticipate good results (from such punishment). (As a matter of fact,) this is a boon conferred on us by You inasmuch as Your punishment to the wicked indeed wipes out their sins. Your wrath itself is esteemed (by us) as a boon (in disguise) in that it has rid our husband of the sin as a result of which the state of a serpent was inflicted on this embodied soul. (I wonder) what austerities were rightly performed in a previous incarnation by this serpent free from pride and bestowing honour on others or else what religious act was done by him out of compassion for all created beings, by virtue of which You, the Giver of life to all, have been pleased (with him). We are unable, 0 Lord, to discover for what (meritorious) act has flowed to him the privilege of touching the dust of Your feet, seeking which (even) Sri (the goddess of beauty and prosperity), a Jewel among women, (whose favour is sought even by Brahma and others) practised austerities for a pretty long period giving up all luxuries and observing sacred vows! Having secured the dust of Your feet people neither covet the uppermost heaven (the realm of Brahma) nor the rulership of the entire globe nor the position of Brahma (the highest functionary of this universe) nor dominion over the subterranean regions nor the mystic powers of Yoga nor (even) final beatitude (the cessation of rebirth).