Srimad-Bhagavatam: Canto 8 - Chapter 1 - Verse 16
Sanskrit:
मथ्यमानात् तथा सिन्धोर्देवासुरवरूथपै: ।यदा सुधा न जायेत निर्ममन्थाजित: स्वयम् ॥ १६ ॥
ITRANS:
mathyamānāt tathā sindhordevāsura-varūtha-paiḥyadā sudhā na jāyetanirmamanthājitaḥ svayam
Translation:
When nectar did not come from the Ocean of Milk, despite so much endeavor by the best of the demigods and demons, the Supreme Personality of Godhead, Ajita, personally began to churn the ocean.