Skandapurana 16.205.13

16.205.13

trīṇi śrāddhe pavitrāṇi dauhitraḥ kutapastilāḥ ..
trīṇi cātra praśaṃsaṃti śuddhimakrodhamatvarām .. 13 ..

Three things are purifying in a śrāddha: a daughter's son, the kutapa period, and sesame seeds; / and here they praise three things: purity, absence of anger, and lack of haste.