The works of Ādi Śaṅkarācārya

Chāndogyopaniṣadbhāṣyam

Verse 228

यन्तो मनसैवामिति प्रविवेश ह वाक् ॥

In plain words

Moving with the mind alone, speech re-entered.

Close to the Sanskrit

Controlling with the mind indeed thus, speech entered indeed.