Tejobindu Upanishad 1.32
अहं ब्रह्मेति निश्चयः । अनात्मन्यात्मविज्ञानं नात्मा बुद्धिः शरीरकम्
Ahaṁ brahmeti niścayaḥ, anātmany ātma-vijñānaṁ nātmā buddhiḥ śarīrakam
"I am Brahman" — this is the firm conviction. Knowing the Self in what is not-Self is bondage; the body and intellect are not the Atman.