Kauṣītaki Upaniṣad 3.2.5

3.2.5

yāvad dhy asmiñ charīre prāṇo vasati tāvad āyuḥ /

2. Then he said: ‘I am the breathing spirit (_prāṇa_), the intelligential self (_prajñātman_). As such (_tam_), reverence me as life (_āyus_), as immortality. Life is the breathing spirit. The breathing spirit, verily, is life. The breathing spirit, indeed, is immortality. For, as long as the breathing spirit remains in this body, so long is there life. For indeed, with the breathing spirit in this world one obtains immortality; with intelligence, true conception (_saṃkalpa_).