The works of Ādi Śaṅkarācārya

Chāndogyopaniṣadbhāṣyam

Verse 3

कतमा कतमर्कतमतत्साम कतम-कतम उद्गीथ इति विमृष्ट भवति ॥ ४ ॥

In plain words

Which indeed is the Rig? Which is that Saman? And which indeed is the Udgitha? These are the questions that are deeply investigated.

Close to the Sanskrit

Which is which Rig? Which is that Saman? Which is which Udgitha? Thus it is deliberated.