Kauṣītaki (Śāṅkhāyana) Brāhmaṇa 18.9.2

18.9.2

garbhasya tvaco vapā rūpam phālī karaṇān garbham iti śāmitre śrapayitvā itarasya vaṣaṭ kāreṣu śāmitra eva juhuyuḥ / (soma: avabhṛtha)

Cooking the skin of the embryo in the form of the omentum, the husks of grain, [and] the embryo in the slaughterer’s hearth, they should offer them in the slaughterer’s hearth at the vaṣaṭ-calls of the other.