Śatapatha Brāhmaṇa ("of a hundred paths") 1.2.3.5

1.2.3.5

tato devāḥ | etām darśapūrṇamāsayordakṣiṇāmakalpanyadanvāhāryaṃ nedadakṣiṇaṃ havirasaditi tannānā ninayati tathaibhyo 'samadaṃ karoti tadabhitapati tathaiṣāṃ śṛtam bhavati sa ninayati tritāya tvā dvitāya tvaikatāya tveti paśurha vā eṣa ālabhyate yatpuroḍāśaḥ

Thereupon the gods ordained this to be the dakshinâ at the new- and full-moon sacrifices, to wit, the Anvâhârya mess of rice, 'lest the oblation should be without a dakshinâ.' That (rinsing water) he pours out (for each Âptya) separately: thus he avoids a quarrel among them. He makes it hot (previously): thus it becomes boiled (drinkable) for them. He pours it out with the formulas, 'For Trita thee!' 'For Dvita thee!' 'For Ekata thee!'--Now it is as an animal sacrifice that this sacrificial cake is offered.