Sankaracarya's Vivekachudamani 441

न प्रत्यग्ब्रह्मणोर्भेदं कदापि ब्रह्मसर्गयोः ।

प्रज्ञया यो विजानिति स जीवन्मुक्तलक्षणः ॥

na pratyagbrahmaṇorbhedaṃ kadāpi brahmasargayoḥ |

prajñayā yo vijāniti sa jīvanmuktalakṣaṇaḥ ||

(Sankaracarya's Vivekachudamani 441)

One who, through direct Knowledge, never sees any distinction between the Self and Brahman and between the universe and Brahman, such a person is considered to possess the marks of a jivan-mukta.