Maitri (Maitrāyaṇīya) Upaniṣad 6.16

6.16

vigrahavāneṣa kālaḥ sindhurājaḥ prajānām eṣa tatsthaḥ savitākhyo yasmādeveme candrarkṣagraha saṃvatsarādayaḥ sūyante athaibhyaḥ sarvamidamatra vā yatkiñcitśubhāśubhaṃ dṛśyanteha loke tadetebhyastasmādādityātmā brahmātha kālasaṃjñamādityamupāsītādityo brahmetyeke'tha evaṃ hyāha |
hotā bhoktā havirmantro yajño viṣṇuḥ prajāpatiḥ |
sarvaḥ kaścitprabhuḥ sākṣī yo'muṣminbhāti maṇḍale ||

16. This embodied Time is the great ocean of creatures. In it abides he who is called Savitṛi, from whom, indeed, are begotten moon, stars, planets, the year, and these other things.

And from them comes this whole world here, and whatever thing, good or evil, may be seen in the world. Therefore Brahma is the soul (ātman) of the sun. So, one should reverence the sun as a name of Time. Some say: ‘Brahma is the sun.’ Moreover it has been said:—

The offerer, the enjoyer, the oblation, the sacrificial formula (mantra), The sacrifice, Vishṇu, Prajāpati— Every one whatsoever is the Lord (prabhu), the Witness, Who shines in yonder orb.