Śatapatha Brāhmaṇa ("of a hundred paths") 9.3.4.16

9.3.4.16

agnau hutvāthainamabhiṣiñcati | daivo vā asyaiṣa ātmā mānuṣo 'yaṃ devā u vā agre 'tha manuṣyāstasmādagnau hutvāthainaṃ tasyaiva pariṣiṣṭenābhiṣiñcatyatra taṃ sruvamanuprāsyati

He anoints him after making offering on the fire-altar, for that (altar) is his divine body, and this (Sacrificer himself) is his human one; and the gods indeed were first, and thereafter the men: therefore, after making offering, he anoints him with what remains over of that same (offering-material). He then throws the dipping-spoon after (the oblations into the fire).