Vaishnava Dharmashastra 90.19

90.19

pauṣyāṃ samatītāyāṃ kṛṣṇapakṣadvādaśyāṃ sopavāsas tilaiḥ snātas tilokakaṃ dattvā tilair vāsudevam abhyarcya tān eva hutvā dattvā bhuktvā ca pāpebhyaḥ pūto bhavati ||

If on the twelfth day of the dark half following on the full moon day of the month Pausha, he washes himself, after having kept a fast, with sesamum-seeds, gives water mixed with sesamum
(to the manes), worships Vâsudeva with sesamum, offers up (part of) the same in fire, gives to Brâhmanas of it, and eats (the remainder himself) he is purified from his sins.