Bhagavad Gita 8.19
भूतग्रामः स अवायं भूत्वा भूत्वा प्रलीयते |
रात्रिगमेऽवश: पार्थ प्रभात्यहरगमे
Translation
Multitudes of beings repeatedly take birth with the advent of Brahma’s day, and are reabsorbed on the arrival of the cosmic night, to manifest again automatically on the advent of the next cosmic day.