Śatapatha Brāhmaṇa ("of a hundred paths") 3.7.3.5

3.7.3.5

ta uparudhyaiva paśūn | agnim mathitvāgnāvagnimajuhuvuste 'vidureṣa vai kila haviṣo yāma eṣā pratiṣṭhāgnau vai kila havirjuhvatīti tato 'bhyavāyaṃstato rātamanasa ālambhāyābhavan

Having, then, first secured the animals, and churned the fire, they offered fire into the fire; and then they (the animals) knew that this truly is the manner of sacrificial food, this its resort; that it is truly in fire that sacrificial food is offered. And accordingly they resigned themselves, and became favourably disposed to the slaughtering.