Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: Sayyiduna Sa’d bin Ubadah (may Allah be pleased with him) asked the Prophet Muhammad (peace and blessings be upon him) about a vow that was obligatory upon his mother, and his mother passed away before fulfilling that vow. So the Prophet Muhammad (peace and blessings be upon him) said to him:“You should fulfill it on her behalf.”