What is Brahman's day covers a thousand such cycles. His night also covers a thousand similar cycles. They who know this are said to know the day and the night.
सहस्रयुगपर्यन्तमहर्यब्रह्मणो विदुः। रात्रिं युगसहस्रान्तां तेऽहोरात्रविदो जनाः॥