Śatapatha Brāhmaṇa ("of a hundred paths") 10.5.2.15

10.5.2.15

tadetaddevavrataṃ rājanyabandhavo manuṣyāṇāmanutamāṃ gopāyanti tasmādu teṣu vīryavānjāyate'mṛtavākā vayasāṃ sā kṣipraśyenaṃ janayati

And when he is asleep, he does not, by means of them, know of anything whatever, nor does he form any resolution with his mind, or distinguish the taste of food with (the channel of) his speech, or distinguish any smell with (the channel of) his breath; neither does he see with his eye, nor hear with his ear, for those (vital airs) have taken possession of him. Whilst being one only, he (the man in the eye) is numerously distributed among living beings: whence the Lokamprinâ (representing the man in the sun), whilst being one only (in kind), extends over the whole altar; and because he (the man in the eye) is one only, therefore (the Lokamprinâ) is one.