It is narrated from Hazrat Sa'd bin Ubadah (may Allah be pleased with him) that once he presented himself before the Noble Prophet (peace and blessings be upon him) and said, "My mother has passed away. She had made a vow. Will it suffice if I free a slave on her behalf?" The Noble Prophet (peace and blessings be upon him) said, "You can free a slave on behalf of your mother."