Skandapurana 10.82

10.82

oṃ viṣṇurūpa dvijaśreṣṭha bhūdeva paṅktipāvana .
sadakṣiṇā mayā dattā tubhyaṃ vaitaraṇi namaḥ .
iti dānamantraḥ .. 159.82 ..

“Oṃ. You who are a form of Viṣṇu, best of the twice-born, earthly god, sanctifier of the row,
this [cow] is given by me with a sacrificial fee; homage to you, O Vaitaraṇī!”
Such is the gift mantra.