Śatapatha Brāhmaṇa ("of a hundred paths") 8.7.3.1

8.7.3.1

atha purīṣaṃ nivapati | māṃsaṃ vai purīṣam māṃsenaivainametatpracādayatīṣṭakā upadhāyāsyīṣṭakā asthi tanmāṃsaiḥ saṃcādayati

He now throws loose soil (on the layer); for the loose soil means flesh: he thus covers him (Agni) with flesh. [He does so] after having laid down the bricks;--the bricks are the bone: he thus covers the bone with flesh.