Śatapatha Brāhmaṇa ("of a hundred paths") 4.3.4.11

4.3.4.11

athāgnīdhre | dve vaikāṃ vā juhoti tadyadagnāvāgnīdhre dve vaikāṃ vā juhotyagnirvai paśūnāmīṣṭe ta enamabhitaḥ pariṇiviśante tametayāhutyā prīṇāti so 'smai prīto 'numanyate tenānumatāṃ dadāti

He then makes either one or two oblations on the Âgnîdhra (fire). The reason why he makes one or two oblations on the Âgnîdhra fire is that Agni rules over beasts (cattle), and they lie round about him on every side: it is him he pleases by this oblation, and thus pleased he is gracious unto this (sacrificer), and the latter offers (to the priests a cow) graciously given up by him (Agni).