Garudapurana 1.218.13

1.218.13

Having offered sandalwood paste and flowers with both hands and raised the ancestor-vessel, reciting "The divine [waters]...", [he says:] "O our father of such-and-such gotra, such-and-such devaśarman, together with your wife, this is your arghya, svadhā!" / Taking the vessel without the strainer, upon kuśa grass to the left and south, [saying,] "Om, you are a seat for the ancestors," the vessel is placed upside down.