Bhagavatapurana 2.9.8

2.9.8

divyaṃ sahasrābdam amoghadarśano jitānilātmā vijitobhayendriyaḥ /
atapyata smākhilalokatāpanaṃ tapastapīyāṃstapatāṃ samāhitaḥ //

8. Brahma whose view (understanding of the utterance) was not untrue, controlled his breaths and mind, restrained both organs (the sense organs and the physical organs) and in perfect serenity of mind for a period of a thousand years according to celestial measure, performed a Tapas which conferred on him (discovered to him) the light in which all the worlds were seen (the plan of the worlds was seen); for he is the foremost Tapasvin among those that perform Tapas.