Offering Du`a' for the dead when washing or enshrouding them (Part No. 2; Page No. 535) is permissible, for Du`a' benefits the dead. However, if it is offered in unison along with raising the hands, this is an act of Bid`ah (innovation in religion) that has no evidence in Shari`ah. Offering Du`a' for the dead after burial individually and in congregation is permissible. It is authentically reported that the Prophet (peace be upon him) stood by the grave of a dead person after burial and supplicated:
Ask Allah's forgiveness for your brother and beg steadfastness for him, for he will now be questioned
.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.