Garudapurana 1.218.4

1.218.4

tato dakṣiṇā bhimukhena vāmopavītenāmukagotrebhyo asmatpitṛpitāmahaprapitāmahebhyo yathānāmaśarmabhya etatpādodakamarghyaṃ svadheti pitrādibrāhmaṇapādayoḥ pitṛtīrthena ābhugnakuśakusumasahitajaladānam //

Then, facing south, with the sacred thread worn on the right shoulder, saying: 'To our fathers, grandfathers, and great-grandfathers belonging to such-and-such gotra, bearing such-and-such names, may this foot-washing water and arghya offering be svadhā', the giving of water accompanied by bent kuśa grass and flowers at the feet of the brāhmaṇas representing the father and others, via the pitṛtīrtha.