Kauṣītaki Upaniṣad 4.18

4.18.1

sa hovāca bālākir ya evaiṣa savye 'kṣiṇi puruṣas tam evāham upāsa iti /

18. Then said Bālāki: ‘Him who is this person in the left eye—him indeed I reverence.’ To him then Ajātaśatru said: ‘Make me not to converse on him! As the soul of Truth, the soul of lightning, the soul of brightness—thus, verily, I reverence him.’

4.18.2

taṃ hovācājātaśatrur mā maitasmin saṃvādayiṣṭhāḥ /

4.18.3

satyasyātmā vidyuta ātmā tejasa ātmeti vā aham etam upāsa iti /

4.18.4

sa yo haitam evam upāsta eteṣāṃ sarveṣām ātmā bhavati //18//

He then who reverences him thus, becomes the soul of all these.