The Mukhya Upaniṣads

Kena · Khaṇḍa 1 · The Light Behind Mind and Senses

Mantra 9

यत्प्राणेन न प्राणिति येन प्राणः प्रणीयते ।तदेव ब्रह्म त्वं विद्धि नेदं यदिदमुपासते ॥ ९ ॥

In plain words

That which life-breath does not enliven, but by which life-breath is moved—know That alone as Brahman, not this limited object that people worship.