Kauṣītaki (Śāṅkhāyana) Brāhmaṇa 1.3.10

1.3.10

prayājān me anuyājāṃś ca kevalān ghṛtam ca apām puruṣam ca oṣadhīnām iti / (agnyādhāna)

i. 2. The gods and the Asuras were in conflict over these worlds. From them Agni departed, and entered the seasons. The gods, having been victorious and having slain the Asuras, sought for him; Yama and Varuṇa discerned him. Him (the gods) invited, him they instructed, to him they offered a boon. He chose this as a boon, '(Give) me the fore-offerings and the after-offerings for my own, and the ghee of the waters and the male of plants.' Therefore they say 'Agni's are the fore-offerings and the after-offerings; Agni's is the butter.' Then indeed did the gods prosper, the Asuras were defeated. He prospers himself, his foe is defeated, who knows thus.