It is narrated from Hazrat Wathilah (may Allah be pleased with him) that some people from Banu Sulaym once came to the service of the Prophet (peace and blessings be upon him) and said, "One of our companions has made the fire of Hell obligatory upon himself by killing a person.?" The Prophet (peace and blessings be upon him) said: "He should free a slave, so that Allah Almighty will free each of his limbs from the fire of Hell in exchange for each limb of that slave."