Bhagavadgita 2.43

Bhagavadgītābhāṣya (Śāṅkarabhāṣya) 2.43

nāsato vidyate bhāvo nābhāvo vidyate sataḥ |
ubhayor api dṛṣṭo 'ntas tv anayos tattva-darśibhiḥ ||