The Mukhya Upaniṣads

Kena · Khaṇḍa 1 · The Light Behind Mind and Senses

Mantra 2

श्रोत्रस्य श्रोत्रं मनसो मनो यद् वाचो ह वाचं स उ प्राणस्य प्राणः ।चक्षुषश्चक्षुरतिमुच्य धीराः प्रेत्यास्माल्लोकादमृता भवन्ति ॥ २ ॥

In plain words

That which is the hearing of hearing, the mind of mind, the speech of speech, the life of life, and the sight of sight—the wise, relinquishing identification with these faculties, become immortal when they depart from this world.