Śatapatha Brāhmaṇa ("of a hundred paths") 8.7.3.17

8.7.3.17

tadyaiṣottamā svayamātṛṇā | etadasya tadātmanastadyadetāmatropadadhāti yadevāsyaiṣātmanastadasminnetatpratidadhāti tasmādetāmatropadadhāti

Now that last self-perforated (brick) is just that part of him (Pragâpati-Agni); and when he now lays it down in this place, he thereby restores to him what part of his body this is: that is why he lays it down in this place.