Bṛhadāraṇyaka Upaniṣad ("Great Forest Teaching") 2.1.3

2.1.3

sa hovāca gārgyo yaevāsau candre puruṣa etamevāhaṃ brahmopāsa iti sahovācājātaśatrurmā maitasminsaṃvadiṣṭhā bṛhanpāṇḍaravāsāḥ somo rājeti vā ahametamupāsa iti sa ya etamevamupāste'haraharha sutaḥ prasuto bhavati nāsyānnaṃ kṣīyate

Gârgya said: 'The person that is in the moon (and in the mind), that I adore as Brahman.' Agâtasatru said to him: 'No, no! Do not speak to me on this. I adore him verily as the great, clad in white raiment, as Soma, the king.' Whoso adores him thus, Soma is poured out and poured forth for him day by day, and his food does not fail.