Mbh 13.127.4

"'"Gargya said, 'One should always do the duties of hospitality to one's guests. One should give lamps in the hall or shed where sacrifices are performed. One should avoid sleep during the day, and abstain from all kinds of flesh or food. One should never injure kine and Brahmanas. One should always recite names of the Pushkara lakes and the other sacred waters. Such a course of duty, is the foremost. Even this constitutes a high religion with its mysteries. If observed in practice, it is sure to produce great consequences. If a person performs even a hundred sacrifices, he is doomed to see the exhaustion of the merits attaching to the libations poured therein. The duties, however, which I have mentioned are such that when observed by a person endued with faith, their merit becomes inexhaustible. Listen now to another high mystery concealed from the view of many. The deities do not accept the libations (poured upon the fire) on the occasion of Sraddhas and rites in their honour or on the occasion of those rites that are performable on ordinary lunar days or on the especially sacred days of the full moon and the new moon, if they behold a woman in her season of impurity or one that is the daughter of a mother afflicted with leprosy. The Pitris of the man who allows such a woman to come near the place where the Sraddha is being performed by him, do not become gratified with him for thirteen years. Robed in raiment of white, and becoming pure in body and mind, one should invite Brahmanas and cause them to utter their benedictions (when one performs the Sraddha). On such occasions one should also recite the Bharata. It is by observing all these that the offerings made at Sraddhas become inexhaustible.'