Hadhrat Abu Hurayra (Radhiallaahu Anhu) narrates that Rasulullah (Sallallaahu Alayhi Wasallam) said, "Allah Ta'ala will elevate the ranks of the Muslims in paradise. A person will say, 'O My Rabb! How did I get this high rank?' Allah Ta'ala will say, 'Your children prayed for your pardon and it is due to the Du'aas of your children, I have granted you this position.'"

Hadhrat Abdullah ibn Abbaas (Radhiallaahu Anhu) narrates that Rasulullah (Saliallaahu Alayhi Wasallam) said, "The deceased in the grave is like a drowning person screaming for help and assistance." He waits for help from the people of the world through gifts of virtuous deeds, Du'aas, etc.

When anyone sends a gift to him, he regards the entire world insignificant in comparison to that gift. Due to the Du'aas of the living, Allah Ta'ala bestows upon the deceased rewards equivalent to the mountains.

If parents want to benefit from virtuous deeds of their children after death, they should sacrifice in making their children pious. This is generally possible by imbuing one's children with Ilm-e-Deen and instilling in them Islamic values and principles. That will be the driving force behind one benefiting from the virtuous deeds and Du'aas of one's children after death.