Kaushitakagrihyasutra 5.3.3

5.3.3

jīvantyā vṛkkau pṛṣṭhata uddhṛtya saṃjñaptāyā vā dakṣiṇāgnau koṣṇau kṛtvā ati drava ityṛgbhyāṃ pāṇayorādhāya \3\

Having extracted the two kidneys from behind while she is alive, or having slaughtered her, and warmed them on the dakṣiṇa fire, he places them into his two hands with the two verses: "Run past...";