While the mystic sage thus concentrated his mind by powerful yoga practice, the tremendous period of six lifetimes of Manu passed by.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
तस्यैवं युञ्जतश्चित्तं महायोगेन योगिनः । व्यतीयाय महान् कालो मन्वन्तरषडात्मकः
tasyaivaṃ yuñjataścittaṃ mahāyogena yoginaḥ | vyatīyāya mahān kālo manvantaraṣaḍātmakaḥ
SB 12.8.14