Śāṅkhāyana (Kauṣītaki) Āraṇyaka 7.3

7.3

ŚĀ 7,3
śākalyasya pṛthivyagniḥ pṛthivī vāg anuvyāhārāḥ | sa yadi nirbhujaḥ khalu vai vayaṃ madhyamo vāk prāṇena mātā jāyā prajñā vāg bṛhadgatirvālisarvamuttamam ||

ŚĀ 7.3
According to Śākalya: earth, Agni; earth, speech, the subsequent utterances. If he is the Nirbhuja indeed, we [say]: the middle one is speech; by breath, mother, wife, consciousness, speech, the great course, all of it is the highest.