Bhagavad Gita · 8.18

अव्यक्ताद्व्यक्तयः सर्वाः प्रभवन्त्यहरागमे।रात्र्यागमे प्रलीयन्ते तत्रैवाव्यक्तसंज्ञके॥

avyaktād vyaktayaḥ sarvāḥ prabhavanty ahar-āgame rātry-āgame pralīyante tatraivāvyakta-sañjñake

At the arrival of Brahma's day, all manifest beings come forth from the unmanifest, and at the fall of his night, they dissolve into that which is called the unmanifest.

— Bhagavad Gita 8.18

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)