It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that Sayyiduna Sa'd bin Ubadah (may Allah be pleased with him) asked the Messenger of Allah (peace and blessings be upon him) about a vow that was due from his mother, and he (peace and blessings be upon him) ordered him to fulfil it.
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5345