Rigvidhana 1.5.25

1.5.25

sarasvatyai tathā viṣṇor antyā sauviṣṭakṛty api./
ājya āhutaya eva ādau sthālī pāke hute punaḥ.//

to Sarasvatī, and to Viṣṇu, and the final one is the Sviṣṭakṛt oblation. / There are offerings of ghee at the beginning, but once the cooked mess of grain has been offered,