Shatapatha Brahmana 10.1.4.7

10.1.4.7

ṣaṣṭhīṃ citiṃ cinoti sā hāsyaiṣā vāgevatadvai tadamṛ tamamṛtaṃ hi vākṣaiṣāmṛtacitistadetanmartyamubhayato'mṛtena parigṛhṇāti tenāsyaitadamṛtam bhavatyatha puriṣaṃ nivapati taddhāsyaitadasṛgeva tvageva tadvai tanmartyam martyaṃ hyasṛṅmartyā tvaktadetasminnamṛte pratiṣṭhāpayati tenāsyaitadamṛtam bhavati

He lays down the sixth layer,--this, doubtless, is his voice, and it is an immortal (element), for the voice is something immortal: this, then, is an immortal layer. He thus encompasses that mortal (element) on both sides by an immortal one, and thereby that part of him becomes immortal. He then scatters loose soil thereon,--this, doubtless, is his blood and his skin, and it is a mortal (element), for blood is mortal, and skin is mortal: he establishes it on that immortal (element), and thereby this part of him becomes immortal.