Śatapatha Brāhmaṇa ("of a hundred paths") 2.5.2.30

2.5.2.30

pratiparāṇīyodaiti pratiprasthātā | sammṛjantyagniṃ sammṛṣṭe 'gnau tā ubhāvevottarāvāghārāvāghārayato 'thādhvaryurevāśrāvya hotāram pravṛṇīte pravṛto hotottarasyai vederhotṛṣadana upaviśatyupaviśya prasauti tā ubhāveva prasūtau sruca ādāyātikrāmato 'tikramyāśrāvyādhvaryurevāha samidho yajeti yaja yajeti caturthe-caturthe prayāje samānayamānau navabhiḥ prayājaiścarataḥ

Having led her back (to her seat) the Pratiprasthâtri returns (to his place by the side of the southern altar). They now trim the fire. When the fire has been trimmed, both (the Adhvaryu and Pratiprasthâtri) make the second libation (of butter). Thereupon the Adhvaryu, having called (on the Âgnîdhra) for the 'Sraushat,' chooses the Hotri. The chosen Hotri then seats himself on the Hotri's seat beside the northern altar; and having seated himself, he urges (the Adhvaryu and Pratiprasthâtri) to proceed. Being thus urged to proceed, they both take up the spoons and step across (to the south side of the fires). After stepping across and calling for the 'Sraushat,' the Adhvaryu says (to the Hotri), 'Pronounce the offering-prayer on the kindling-sticks!' and 'Pronounce the offering-prayer!' at each (subsequent fore-offering). Pouring (the butter in the spoons) together (into the guhû) at the fourth, they both proceed with the nine fore-offerings.