Is it permissible to fast on behalf of a living person if he is unable to?

The questioner : Yes, please go ahead. He mentions that his grandmother, when she was young, did not make up the fasts that were obligatory upon her, and she did not fast. He asks: Is it permissible for the mother to make up the fasts for her, since she is now old in age?

The Shaykh : No, no one fasts on behalf of another living person.

The questioner : Even if she does not know how.

The Shaykh : A living person is not fasted for, whether he is able or unable. Fasting on behalf of the deceased is only for one who died with fasts owed to him; his guardian fasts for him. If the hadith had not come with this ruling, we would say that no one fasts on behalf of another, because these are acts of worship that a person is required to perform himself so that they bring him closer to Allah the Exalted and so that they serve as a connection between him and his Lord. However, the Sunnah has come with this ruling.