Kaṭha Upaniṣad 2.14.p1

2.14.p1

sarve vedā yat padam āmananti tapāṃsi sarvāṇi ca yad vadanti /
yad icchanto brahmacaryaṃ caranti tat te padaṃ saṃgraheṇa bravīmi //

15. The word which all the Vedas rehearse,
And which all austerities proclaim,

Desiring which men live the life of religious studentship (_brahmacarya_)— That word to thee I briefly declare. That is _Om_! 16. That syllable, truly, indeed, is Brahma! That syllable indeed is the supreme! Knowing that syllable, truly, indeed, Whatever one desires is his! 17. That is the best support. That is the supreme support. Knowing that support, One becomes happy in the Brahma-world.