Chandogya Upanishad 5.1.8

5.1.8

sā ha vāg uccakrāma \
sā saṃvatsaraṃ proṣya paryetyovāca \
katham aśakatarte maj jīvitum iti \
yathā kalā avadantaḥ prāṇantaḥ prāṇena paśyantaś cakṣuṣā śṛṇvantaḥ śrotreṇa dhyāyanto manasaivam iti \
praviveśa ha vāk \\501.8\

Speech departed. Staying a year out, it came back and asked, 'How have you been able to live without me?' (The others replied,) 'Just like the dumb, though not speaking, yet living with the breath, seeing with the eye, hearing with the ear, and thinking with the mind.' (At this) speech entered (the body).