It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them) that Sayyiduna Sa'd bin Ubadah (may Allah be pleased with him) asked the Messenger of Allah (peace and blessings of Allah be upon him) that my mother has passed away and she had a vow due upon her which she did not fulfill. The Prophet (peace and blessings of Allah be upon him) said: "Fulfill it on her behalf."