etad dhy evākṣaraṁ brahma etad dhy evākṣaraṁ param
etad dhy evākṣaraṁ brahma etad dhy evākṣaraṁ param |
etad dhy evākṣaraṁ jñātvā yo yad icchati tasya tat ||
(Kaṭha Upaniṣad: 1.2.16)
“This one syllable [i.e., Om] is indeed Brahman. This one syllable is indeed supreme. One who knows this one syllable attains that which he desires.”