SB 8.16.47
evam tv ahar ahah kuryad
dvadasaham payo-vratam
harer aradhanam homam
arhanam dvija-tarpanam
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
In this way, until twelve days have passed, one should observe this payo-vrata, worshiping the Lord every day, executing the routine duties, performing sacrifices and feeding the brahmanas.