Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that a woman from the tribe of Juhaynah came to the Prophet (peace and blessings be upon him) and said: My mother vowed to perform Hajj, and she died without performing it. Shall I perform Hajj on her behalf? He (peace and blessings be upon him) said: "Tell me, if your mother had owed a debt, would you have paid it?" She said: Yes. He (peace and blessings be upon him) said: "Then perform Hajj on her behalf and pay what she owes, for Allah, the Mighty and Majestic, is the most entitled to have His due fulfilled."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12391