It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that a man came to the service of the Prophet Muhammad (peace and blessings be upon him) and said: "My mother has passed away, and she had a month of fasting due upon her. Should I fulfill it on her behalf?" The Prophet (peace and blessings be upon him) said: "Tell me! If your mother had a debt, would you pay it off?" He replied: "Yes!" The Prophet (peace and blessings be upon him) said: "Then Allah's debt is more deserving to be fulfilled."
Hadith Referenceمسند اسحاق بن راهويه / كتاب الصوم / 428
Hadith Takhrij«بخاري ، كتاب الصوم ، باب من مات وعليه صوم ، رقم : 1953 . مسلم ، كتاب الصيام ، باب قضاء الصيام عن الميت ، رقم : 1148 . سنن ابوداود ، رقم : 3310 . سنن ترمذي ، رقم : 716 . سنن ابن ماجه ، رقم : 1758 . سنن دارمي ، رقم : 1768 . مسند احمد : 224/1 . صحيح ابن حبان ، رقم : 3530 . صحيح ابن خزيمه ، رقم : 1953 .»
Saeed bin Jubair (may Allah have mercy on him) narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) from the Prophet Muhammad (peace and blessings be upon him) a narration similar to the previous hadith.
Hadith Referenceمسند اسحاق بن راهويه / كتاب الصوم / 429
Saeed bin Jubair (may Allah have mercy on him) narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) from the Prophet Muhammad (peace and blessings be upon him) a narration similar to the previous hadith, and stated: He fulfilled (the fasts) on her (his mother's) behalf.
Hadith Referenceمسند اسحاق بن راهويه / كتاب الصوم / 430
Hadith Takhrij«سنن ابوداود ، كتاب الايمان والنذور ، باب قضاء عن الميت ، رقم : 3307 . قال الشيخ الالباني : صحيح .»