Srimad-Bhagavatam: Canto 12 - Chapter 1 - Verse 14
Sanskrit:
तस्यैवं युञ्जतश्चित्तं महायोगेन योगिन: ।व्यतीयाय महान् कालो मन्वन्तरषडात्मक: ॥ १४ ॥
ITRANS:
tasyaivaṁ yuñjataś cittaṁmahā-yogena yoginaḥvyatīyāya mahān kālomanvantara-ṣaḍ-ātmakaḥ
Translation:
While the mystic sage thus concentrated his mind by powerful yoga practice, the tremendous period of six lifetimes of Manu passed by.