Mbh 13.125.10

"'"The Pitris said, 'Ye highly blessed ones, the doubt existing in your minds has been properly propounded. Listen as we declare what those acts are of righteous men that gratify us. Bulls endued with blue complexion should be set free. Gifts should be made to us, on the day of the new moon, of sesame seeds and water. In the season of rains, lamps should be lighted. By these acts of men, they can free themselves from the debt they owe to the Pitris.[547] Such gifts never become vain. On the other hand, they become inexhaustible and productive of high fruits. The gratification we derive from them is regarded to be inexhaustible. Those men who, endued with faith, beget offspring, rescue their deceased ancestors from miserable Hell'. Hearing these words of the Pitris, Vriddha-Gargya, possessed of wealth of penances and high energy, became filled with wonder so that the hair on his body stood erect. Addressing them he said, 'Ye that are all possessed of wealth of penances, tell us what the merits are that attach to the setting free of bulls endued with blue complexion. What merits, again, attach to the gift of lamps in the season of rains and the gift of water with sesame seeds?'