CHĀNDOGYA UPANISHAD · 1.1.4
कतमा कतम र्क् कतमत् कतमत् साम कतमः कतम उद्गीथ इति विमृष्टं भवति ॥
katamā katama rk katamat katamat sāma katamaḥ katama udgītha iti vimṛṣṭaṃ bhavati ॥
What then is the Rik? What is the Sâman? What is the udgîtha? 'This is the question.
F. Max Müller · The Upanishads, Sacred Books of the East 1 (1879)