Brahma-net Sutra said,
"On the day of the death of parents or brothers, you must invite dharma master to talk about the precepts of Bodhisattva. This is for the purpose of accumulating merit for the deceased so that he will be able to see the Buddha, and be born in human or heaven realm."
It is also said,
"On the day of death of parents, brothers, or guru you must read, recite and conduct sermons on Mahayana sutras."
It is said in the ten directional pure lands sutra of empowerment and rebirth according to wishes:
"Only one seventh of the merit in memorial service will reach the deceased, the rest will be credited to the person who organised it".
- www.tbsn.org
- wong chee tat :)