Bhagavad-gītā 8.17
BG 8.17
Open the full passageसहस्रयुगपर्यन्तमहर्यद् ब्रह्मणो विदुः । रात्रिं युगसहस्रान्तां तेऽहोरात्रविदो जनाः ॥१७॥
Sanskrit
sahasra-yuga-paryantam ahar yad brahmaṇo viduḥ rātriṁ yuga-sahasrāntāṁ te 'ho-rātra-vido janāḥ
Translation
By human calculation, a thousand ages taken together form the duration of Brahmā's one day. And such also is the duration of his night.