Śatapatha Brāhmaṇa ("of a hundred paths") 8.7.3.6

8.7.3.6

sa eṣa prāṇa eva yatpurīṣam | tena sarvamātmānam pracādayati sarvasmiṃstadātmanprāṇaṃ dadhāti tadyaddhāsyaitadaṅgaṃ nābhiprāpnuyātprāṇo hāsya tadaṅgaṃ nābhiprāpnuyādyadu vai prāṇo 'ṅgaṃ nābhiprāpnoti śuṣyati vā vai tanmlāyati vā tasmādenaṃ sarvamevaitena pracādayet

Now this loose soil, indeed, is the vital air; he therewith covers the whole body: he thus puts vital air into the whole body. And, assuredly, whatsoever member thereof he should not reach, that member of him (Agni) the vital air would not reach; and whatever member the vital air does not reach that either dries up or withers away: let him, therefore, cover it entirely therewith.