Majjhima Nikaya

MN 135 Cūḷakammavibhaṅga Sutta:
The Shorter Discourse on the Analysis of Kamma

The Buddha explains actions and their results in a very direct and helpful way.

Vimana Vatthu

Vv 3.8 Mallikā Sutta:
Mallika’s Mansion

Can offerings to the Supreme Buddha after his passing away still give good results?