Markandeyapurana 31.63

31.63

yathā vā dvijamukhyānāṃ paritoṣo 'bhijāyate /
trīṇi śrāddhe pavitrāṇi dauhitraṃ kutapastilāḥ //

or in whatever way the satisfaction of the foremost twice-born is produced. / Three things are purifying in a śrāddha: the daughter's son, the kutapa period, and sesame seeds.