The works of Ādi Śaṅkarācārya

Bṛhadāraṇyakopaniṣadbhāṣyam

Bhashya

Bhashya

तथा अग्निः ।वाचि अग्नेर्विशेषतोऽवस्थानम् ॥

In plain words

Fire works the same way. In your own body, fire's special home is your power of speech.

Close to the Sanskrit

Likewise [for] fire. In speech is the particular seat of fire.