Śatapatha Brāhmaṇa ("of a hundred paths") 4.3.5.7

4.3.5.7

tadyatpratiprasthātā pratinigṛhṇīte | dvidevatyānvai prāviśannasmābhiranuvaṣaṭkṛtā bhaviṣyathetyu hādityā ūcuryāṃ vā amūṃ dvitīyāmāhutiṃ juhoti sviṣṭakṛte vai tāṃ juhoti sviṣṭakṛto vā ete 'nuvaṣaṭkriyante tatho hāsyaite 'nuvaṣaṭkṛtā iṣṭasviṣṭakṛto bhavantyuttarārdhe juhotyeṣā hyetasya devasya diktasmāduttarārdhe juhoti

Thus, the reason why the Pratiprasthâtri draws the Soma-juice, is that they entered into the dvidevatya cups. And the Âdityas then said, 'By us ye shall be supplied with the Anuvashat!' For, that second libation which he (the Pratiprasthâtri) makes, he makes to (Agni) Svishtakrit, and by means of the Svishtakrit these (dvidevatyas) are supplied with the Anuvashat; and thus those (libations) of his are supplied with the Anuvashat, having the (oblation to Agni) Svishtakrit performed for them. He offers on the north part (of the fire), for that is the region of that god: hence he offers on the north part.