Question: Before someone is buried, much attention is paid to washing their body, and before they are taken to the grave, people offer Du`aa’ (supplication) for them. When they reach the grave, people conduct the Funeral Prayer. After this, people offer Du`aa’ again for the dead and then the body is placed into the grave. The earth is heaped on the grave till the body is covered completely, water is splattered on it, a Soorah of the Qur’aan is recited, and people make another Du`aa’ for the third time.
Answer: Offering Du`aa’ for the dead when washing or enshrouding them is permissible, for Du`aa’ benefits the dead… read more here.