Bhagavad Gita · 2.16

नासतो विद्यते भावो नाभावो विद्यते सतः।उभयोरपि दृष्टोऽन्तस्त्वनयोस्तत्त्वदर्शिभिः॥

nāsato vidyate bhāvo nābhāvo vidyate sataḥ ubhayor api dṛṣhṭo 'ntas tv anayos tattva-darśhibhiḥ

The unreal has no existence; the real never ceases to be. The seers of truth have concluded the nature of both.

— Bhagavad Gita 2.16

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