Śatapatha Brāhmaṇa ("of a hundred paths") 2.3.1.21

2.3.1.21

tadu hovāca yājñavalkyaḥ | na vai yajña iva mantavai pākayajña iva vā itīdaṃ hi yadanyasminyajñe srucyavadyati sarvaṃ tadagnau juhotyathaitadagnau hutvotsṛpyācāmati nirleḍhi tadasya pākayajñasyeveti tadasya tatpaśavyaṃ rūpam paśavyo hi pākayajñaḥ

On this point Yâgñavalkya said, 'It (the Agnihotra) must not be looked upon as a (havis-) sacrifice, but as a domestic sacrifice (pâkayagña); for while in any other (havis-)sacrifice he pours into the fire all that he cuts off (from the sacrificial dish and puts) into the offering spoon,--here, after offering and stepping outside, he sips water and licks out (the milk); and this indeed (is a characteristic) of the domestic offering.' This then is the animal characteristic of that (Agnihotra), for the domestic offering pertains to beasts (or cattle).