Garudapurana 1.9.10

1.9.10

taṃ hastaṃ pātayenmūrdhni śiṣyasya tu samāhitaḥ /
haste viṣṇuḥ sthito yasmādviṣṇuhastastatastvayam /
naśyanti sparśanāttasya pātakānyakhilāni ca //

With a concentrated mind, he should place that hand on the head of the disciple. / Because Viṣṇu resides in the hand, this hand is therefore the hand of Viṣṇu; / and from its touch, all sins are destroyed.