Śatapatha Brāhmaṇa ("of a hundred paths") 6.1.2.17

6.1.2.17

tadetā vā asya tāḥ | pañca tanvo vyasraṃsanta loma tvaṅnāṃsamasthi majjā tā evaitāḥ pañca citayastadyatpañca citīścinotyetābhirevainaṃ tattanūbhiścinoti yaccinoti tasmāccitayaḥ

Now it was those five bodily parts (tanu) of his (Pragâpati's) that became relaxed,--hair, skin, flesh, bone, and marrow,--they are these five layers (of the fire-altar); and when he builds up the five layers, thereby he builds him up by those bodily parts; and inasmuch as he builds up (ki), therefore they are layers (kiti).