Śatapatha Brāhmaṇa ("of a hundred paths") 6.6.4.5

6.6.4.5

sa vai nyañjyādeva | devo vā asyaiṣa ātmā mānuṣo 'yaṃ sa yanna nyañjyānna haitaṃ daivamātmānam prīṇīyādatha yannyanakti tatho haitaṃ daivamātmānam prīṇāti sā yatsamittena nāhutiryadu vrate nyaktā tenānnamannaṃ hi vratam

Let him nevertheless dip it in, for that (Âhavanîya fire) is his (the Sacrificer's) divine body, and this (real body of his) is his human one. Now were he not to dip it in, he would not be satisfying that divine body of his; but when he clips it in, he does so satisfy that divine body. And in that it is a kindling-stick, it is not a libation; and in that it is dipped into the fast-milk, it is food, for the fast-milk is food.