Jaiminīya Upaniṣad Brāhmaṇa 3.3.15

3.3.15

sa brūyād yad vācā vadati tad vācaś śarīraṃ yan manasā dhyāyati tan manasaś śarīraṃ yac cakṣuṣā paśyati tac cakṣuṣaś śarīraṃ yac chrotreṇa śṛṇoti tac chrotrasya śarīram
evam u hānye prāṇāś śarīravanto bhavantīti /
prathame 'nuvāke tṛtīyaḥ khaṇḍaḥ //

He should say: "What one speaks with speech, that is the body of speech; what one meditates with mind, that is the body of mind; what one sees with the eye, that is the body of the eye; what one hears with the ear, that is the body of the ear.
Thus indeed do the other breaths possess a body."
[This is] the third khaṇḍa in the first anuvāka.