Śatapatha Brāhmaṇa ("of a hundred paths") 1.5.2.11

1.5.2.11

sa hotā nāpavyāharet | ā vaṣaṭkārāttaṃ vaṣaṭkāreṇāgnāveva yonau reto bhūtaṃ siñcatyagnirvai yoniryajñasya sa tataḥ prajāyata iti nu haviryajñe 'tha saumye 'dhvare

The Hotri must utter nothing improper until his vashat-call. By the vashat-call he pours it (the sacrifice) into the fire, as seed into the womb; for the fire is indeed the womb of the sacrifice, from thence it is brought forth. So now at the havis-sacrifice. And at the Soma-cult,--