Skandapurana 6.3.51.9

6.3.51.9

aṣṭakāsu ca saṃkrāntau vyatīpāte tathaiva ca .
śrāddhakālā ime sarve dattameṣvakṣayaṃ smṛtam .. 51.9 ..

and on the aṣṭakā days, at a saṃkrānti, and likewise on a vyatīpāta. / All these are times for śrāddha; what is given on these is remembered as imperishable.