Skandapurana 5.221.3

5.221.3

śrāddhaṃ teṣāṃ prakartavyaṃ caturdaśyāṃ narādhipa ..
teṣāṃ tasminkṛte tṛptistatastatpakṣajā bhavet .. 3 ..

for them a śrāddha must be performed on the fourteenth day, O ruler of men. / When it is performed on that [day], their satisfaction derived from that fortnight arises.