Śatapatha Brāhmaṇa ("of a hundred paths") 3.7.3.3

3.7.3.3

athopākṛtya paśum | agnim mathitvā niyunakti tadyattathā na ha vā etasmā agre paśavaścakṣamire yaddhavirabhaviṣyanyathainānidaṃ havirbhūtānagnau juhvati tāndevā upanirurudhusta upaniruddhā nopāveyuḥ

Having driven up the victim, and churned the fire, he binds it (to the stake). And as to why this is so:--well, animals did not at first submit thereto that they should become sacrificial food, as they are now become sacrificial food and are offered up in the fire. The gods secured them: even thus secured they did not resign themselves.