Śatapatha Brāhmaṇa ("of a hundred paths") 8.1.4.5

8.1.4.5

tadāhuḥ | kathamasyaiṣo 'gniḥ sarvaḥ kṛtsna iṣṭakāyāmiṣṭakāyāṃ saṃskṛto bhavatīti majjā yajurasthīṣṭakā māṃsaṃ sādanaṃ tvakṣūdadohā loma purīṣasya yajurannam purīṣamevamu hāsyaiṣo 'gniḥ sarvaḥ kṛtsna iṣṭakāyāmiṣṭakāyāṃ saṃskṛto bhavati

Here now they say, 'How does that Agni of his become made up whole and entire in brick after brick?'--Well, the formula is the marrow, the brick the bone, the settling the flesh, the sûdadohas the skins, the formula of the purîsha (fillings of earth) the hair, and the purîsha the food: and thus indeed that Agni of his becomes made up whole and entire in brick after brick.