Shatapatha Brahmana 10.1.4.5

10.1.4.5

caturthīṃ citiṃ cinoti sā hāsyaiṣodāna eva tadvai tadamṛtamamṛtam hyudānaḥ saiṣāmṛtacitistadetanmartyamubhayato'mṛtena parigṛhṇāti tenāsyaitadamṛtam bhavatyatha purīṣaṃ nivapati taddhāsyaitanmāṃsameva tadvai tanmartyam martyaṃ hi māṃsaṃ tadetasminnamṛte pratiṣṭhāpayati tenāsyaitadamṛtam bhavati

He lays down the fourth layer,--this, doubtless, is his upward breathing, and it is an immortal (element), for the upward breathing 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 flesh, and it is a mortal (element), for flesh is mortal: he establishes it on that immortal (element), and thereby this part of him becomes immortal.