Mbh 13.87.3a

"'Bhishma said, "Listen, O king, with close attention, to me as I discourse to you on the ritual of the Sraddha. That ritual is auspicious, worthy of praise, productive of fame and progeny, and is regarded as a sacrifice, O scorcher of foes, in honour of the Pitris. Gods or Asuras or human beings, Gandharvas or Uragas or Rakshasas, Pisachas or Kinnaras,--every one should always worship the Pitris. It is seen that people worship the Pitris first, and gratify the deities next by offering them their adorations. Hence, one should always worship the Pitris with every care.[396] It is said, O king, that the Sraddha performed in honour of the Pitris is performable afterwards. But this general rule is restrained by a special one (which directs that the Sraddha in honour of the Pitris should be performed on the afternoon of the day of the New moon).[397] The (deceased) grandsires become gratified with the Sraddha that may be performed on any day. I shall, however, tell thee now what the merits and demerits are of the respective lunar days (in view of their adaptability to the performance of the Sraddha). I shall discourse to thee, O sinless one, what fruits are attained on what days by performing the Sraddha. Do thou listen to me with close attention. By adoring the Pitris on the first day of the lighted fortnight, one obtains in one's abode beautiful spouses capable of producing many children all possessed of desirable accomplishments. By performing the Sraddha on the second day of the lighted fortnight one gets many daughters. By performing it on the third day, one acquires many steeds. By performing it on the fourth day, one gets a large herd of smaller animals (such as goats and sheep) in one's house. They, O king, who perform the Sraddha on the fifth day, get many sons. Those men who perform the Sraddha on the sixth day acquire great splendour. By performing it on the seventh day, O monarch, one acquires great fame.