Is it permissible to fast, perform prayers on behalf of someone else?

Dear Brother / Sister,

Worships are separated into three as the ones which are performed only physically, the ones which are performed only materially and the ones which are performed both physically and materially. Whichever way you worship, you can always donate the sawab you have earned to someone else. The one to whom sawab has been donated can benefit from it, too.

As for whether one can worship on behalf of someone else, and if he can, whether that person will no longer be responsible for fard and wajib worships or not:

a) It is exactly not permissible to fast, perform prayers and itiqaf (spending at least one day in a mosque or masjid worshipping only) on behalf of someone else. Nobody can fast or perform prayers on behalf of someone else. If these kinds of worships are performed on behalf of someone else, that person is still responsible for performing them.
b) It is exactly permissible to fulfill worships such as alms-giving, adha (sacrificing an animal) and charity, which are performed only materially, on behalf of someone else. One can give alms in person or assign someone else to give alms on his/her behalf.
c) As for worships which are performed both physically and materially such as Hajj (pilgrimage), it is permissible to perform it on behalf of someone else on condition that the person is incapable of performing it himself; otherwise, it is not permissible. Hajj performed on behalf of people who cannot perform it themselves due to death, agedness, continuous disease, having no mahram person to travel to Hajj with (for women) is accepted. People in these situations, and if Hajj is fard upon them, must meet the expenses of Hajj to someone to perform it on their own behalf. When they have someone perform Hajj on their behalf, they are no longer responsible for Hajj.

Performing good deeds and charities on behalf of someone who died as indebted for prayers and donating sawabs of these worships to him/her is favorable.

Questions on Islam