योगवासिष्ठः yogavāsiṣṭhaḥ - book-7, chapter-40, verse-6

नात्मानमवगच्छामि न दृश्यं च जगद्भ्रमम् ।
ब्रह्म शान्तं प्रविष्टोऽस्मि ब्रह्मैवास्मि निरामयः ॥ ६ ॥

nātmānamavagacchāmi na dṛśyaṃ ca jagadbhramam ,
brahma śāntaṃ praviṣṭo'smi brahmaivāsmi nirāmayaḥ 6

6. I know not myself, nor do I understand what this visible and mistaken world may mean; I am absorbed in the calm and quiet Brahma, and feel myself as the sound Brahma himself.