Narrated by Sayyidah Aisha (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) said: Whoever dies while he still has fasts due upon him, then his relative should fast on his behalf.

Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) narrates that a woman came to the service of the Noble Prophet (peace and blessings be upon him) and said: O Messenger of Allah! My mother has passed away, while she still owed a month of fasting. Can I make up the fasts on her behalf? The Prophet (peace and blessings be upon him) said: What do you think—if your mother had a debt, would you have paid it off? She replied: Yes, of course. The Prophet (peace and blessings be upon him) said: Then Allah’s debt is more deserving to be fulfilled.

Narrated by Sayyiduna Abdullah bin Abbas (may Allah be pleased with him): A man came to the service of the Noble Prophet (peace and blessings be upon him) and said: O Messenger of Allah! My mother has passed away, and she had a month of fasting due upon her. Can I make up for it on her behalf? The Prophet (peace and blessings be upon him) said: If your mother had a debt, would you have paid it off? He said: Yes. The Prophet (peace and blessings be upon him) said: Then the debt of Allah is more deserving to be fulfilled.