Chāndogya Upaniṣad 7.3.2

7.3.2

sa yo mano brahmety upāste \
yāvan manaso gataṃ tatrāsya yathākāmacāro bhavati yo mano brahmety upāste \
asti bhagavo manaso bhūya iti \
manaso vāva bhūyo 'stīti \
tan me bhagavān bravītv iti \\703.2\

2. He who reverences Mind as Brahma—as far as Mind goes, so far he has unlimited freedom, he who reverences Mind as Brahma.’

‘Is there, Sir, more than Mind?’

‘There is, assuredly, more than Mind.’

‘Do you, Sir, tell me it.’