Mbh 13.125.3b

In it is contained the ritual in respect of the Sraddha in which have been declared the mysteries connected with the Pitris. The mysteries connected with all the deities have also been explained there. It comprehends the duties and practices, productive of great merit, of the Rishis also, together with the mysteries attaching to them. It contains an exposition of the merits of great sacrifices and those that attach to all kinds of gifts. Those men who always read the scriptures bearing on these topics, those who bear them properly in their mind, and he who, having listened to them, follows them in practice, are all regarded to be as holy and sinless as the puissant Narayana himself. The merits that attach to the gift of kine, those that belong to the performance of ablutions in sacred waters, those that are won by the performance of sacrifices,--all these are acquired by that man who treats guests with reverence. They who listen to these scriptures, they who are endued with faith, and they who have a pure heart, it is well-known, conquer many regions of happiness. Those righteous men who are endued with faith, become cleansed of all stains and no sin can touch them. Such men always increase in righteousness and succeed in attaining to heaven. Once on a time, a celestial messenger, coming to the court of Indra of his own accord, but remaining invisible, addressed the chief of the deities in these words, 'At the command of those two deities who are the foremost of all physicians, and who are endued with every desirable attribute, I have come to this place where I behold human beings and Pitris and the deities assembled together. Why, indeed, is sexual congress interdicted for the man who performs a Sraddha and for him also who eats at a Sraddha (for the particular day)? Why are three rice-balls offered separately at a Sraddha? Unto whom should the first of those balls be offered? Unto whom should the second one be offered?