Srimad-Bhagavatam: Canto 8 - Chapter 1 - Verse 10
Sanskrit:
पयोधिं येन निर्मथ्य सुराणां साधिता सुधा ।भ्रममाणोऽम्भसि धृत: कूर्मरूपेण मन्दर: ॥ १० ॥
ITRANS:
payodhiṁ yena nirmathyasurāṇāṁ sādhitā sudhābhramamāṇo ’mbhasi dhṛtaḥkūrma-rūpeṇa mandaraḥ
Translation:
By churning the Ocean of Milk, Ajita produced nectar for the demigods. In the form of a tortoise, He moved here and there, carrying on His back the great mountain known as Mandara.