What is the reward that a son receives if he performs Hajj on behalf of his deceased father: Is it solely the reward for filial piety, or does it also include the reward for Hajj?

Whoever helps a person in an act of obedience will receive a reward similar to that act. If someone equips a warrior for battle, or looks after his family in his absence, or carries out the command of a charitable person, he will receive a reward similar to that of the warrior or the charitable person. Therefore, whoever performs Hajj on behalf of his deceased or incapacitated father will receive a reward similar to that of the pilgrim, because he has performed the entire act of obedience. The prophetic traditions that encourage Hajj do not differentiate between performing Hajj for oneself or on behalf of another. Furthermore, witnessing the sacred rites and showing filial piety to one's parents by performing Hajj on their behalf carries a great reward.