It is narrated from Hazrat Ibn Abbas (may Allah be pleased with them both) that Sa’d bin Ubadah asked the Prophet (peace and blessings be upon him) about a vow that was obligatory upon his mother, but she passed away before fulfilling it. The Prophet (peace and blessings be upon him) said: Fulfill that vow on her behalf.

Hazrat Ibn Buraidah narrates from his father that I was sitting in the blessed service of the Prophet (peace and blessings be upon him) when a woman came and said: "My mother had two months of fasts (obligatory) upon her. Can I fast on her behalf?" The Prophet (peace and blessings be upon him) said: "You should fast on her behalf. Tell me, if your mother had a debt and you paid it off, would that be sufficient?" She replied: "Why not." The Prophet (peace and blessings be upon him) said: "Then you should fast on her behalf."

Hazrat Sinan bin Abdullah Juhani narrates that his paternal aunt told him that she went to the Noble Prophet (peace and blessings be upon him) and said: O Messenger of Allah! My mother passed away in a state that she had made a vow to walk to Makkah. The Prophet (peace and blessings be upon him) said: Can you walk to Makkah on her behalf? She said: Yes! The Prophet (peace and blessings be upon him) said: Then walk to Makkah on her behalf. The questioner asked: Will this suffice for her? The Prophet (peace and blessings be upon him) said: Yes! And he said: Tell me, if your mother had a debt and you paid it off, would it be accepted on behalf of your mother? She replied: Yes! The Prophet (peace and blessings be upon him) said: Allah is more deserving (that His right be fulfilled). And (Imam) Abu Hanifa’s opinion has been mentioned that: This will not suffice for the deceased.