Bhagavatapurana 8.7.4

8.7.4

svādhyāyaśrutasampannāḥ prakhyātā janmakarmabhiḥ /
iti tūṣṇīṃ sthitān daityān vilokya puruṣottamaḥ /
smayamāno visṛjyāgraṃ pucchaṃ jagrāha sāmaraḥ //

3 & 4. The great Daityas did not like that act of the Supreme Person and said "we shall not hold the ugly tail of the serpent, for we are well versed in Vedic and Sastraic learning and also famous for our (noble) birth and deeds" Purushothama observed the Daityas standing quiet and aloof with this notion in their mind.

5 & 6. Putting on a smile, He left off the fore part and took hold of the tail, the Immortals following Him. Having thus appointed places for themselves, the sons of Kasyapa churned the sea of milk for Amrita putting forth all their strength and attention; when the sea was being (thus) churned, the unsupported mount went down into the water.