Mbh 13.91.2a

"'Bhishma said, "Listen to me, O ruler of men, as I tell thee how the Sraddha was introduced, the time of such introduction, the essences of the rite, and the Muni who conceived it. From the Self-born Brahman sprang Atri, O thou of Kuru's race. In Atri's race was born a Muni of the name of Dattatreya. Dattatreya got a son of the name of Nimi possessed of wealth of asceticism. Nimi got a son named Srimat who was endued with great beauty of person. Upon the expiration of a full thousand years, Srimat, having undergone the severest austerities, succumbed to the influence of Time and departed from this world. His sire Nimi, having performed the Purificatory rites according to the ritual laid down in the ordinance, became filled with great grief, thinking continually of the loss of his son.[411] Thinking of that cause of sorrow the high-souled Nimi collected together various agreeable objects (of food and drink) on the fourteenth day of the moon. The next morning he rose from bed. Pained his heart was with grief, as he rose from sleep that day--he succeeded in withdrawing it from the one object upon which it had been working. His understanding succeeded in busying itself with other matters. With concentrated attention he then conceived the idea of a Sraddha. All those articles of his own food, consisting of fruits and roots, and all those kinds of staple grains that were agreeable to him, were carefully thought of by that sage possessed of wealth of penances. On the day of the New moon he invited a number of adorable Brahmanas (to his asylum). Possessed of great wisdom, Nimi caused them to be seated on seats (of Kusa grass) and honoured them by going around their persons. Approaching seven such Brahmanas whom he had brought to his abode together, the puissant Nimi gave unto them food consisting of Syamaka rice, unmixed with salt.