Skanda Purana 1.4.3.124

1.4.3.124

etāścatasrastithayo yugādyā dattaṃ hutaṃ cākṣayamāśu vidyāt..
yugeyuge varṣaśatena dānaṃ yugādikāle divasena tatphalam.. 5.124 ..

One should know that what is given and offered on these four lunar days, the beginnings of the yugas, becomes imperishable at once: / the gift given during a hundred years in each yuga yields that same fruit in a single day at the time of a yuga's beginning.