Bhagavad Gita 13.12

ज्ञेयं यत्तत्प्रवक्ष्यामि यज्ज्ञात्वामृतमश्नुते।
अनादिमत्परं ब्रह्म न सत्तन्नासदुच्यते ॥

jñeyaṃ yat-tat-pravakṣyāmi yajjñātvāmṛtam-aśnute
anādimat-paraṃ brahma na sat-tannāsad-ucyate – 12

I shall now describe clearly that which should be known, knowing which one attains immortality. It is the beginningless, supreme Brahman, which is neither existence nor non-existence.