Manava Dharmashastra 1.12

1.12

tasminn aṇḍe sa bhagavān uṣitvā parivatsaram
svayam evātmano dhyānāt tad aṇḍam akarod dvidhā //

The divine one resided in that egg during a whole year, then he himself by his thought (alone) divided it into two halves;