The works of Ādi Śaṅkarācārya

Bṛhadāraṇyakopaniṣadbhāṣyam

Verse 24

एष उ एव ब्रह्मणस्पतिर्वाग्वै ब्रह्म

In plain words

This very prāṇa is Brahmaṇaspati; speech is indeed Brahman.

Close to the Sanskrit

This one indeed is Brahmaṇaspati, speech verily is Brahman.