It is narrated from Qays bin Abi Hazim (may Allah have mercy on him) that the Messenger of Allah (peace and blessings be upon him) sent Sayyiduna Khalid bin al-Walid (may Allah be pleased with him) to some people of the tribe of Khath'am. They tried to protect themselves by prostrating, showing their Islam, but Khalid (may Allah be pleased with him) killed them. So the Messenger of Allah (peace and blessings be upon him) paid their heirs half the blood money, then said: "I am free of every Muslim who lives among the polytheists; the fires of the two should not be visible to each other."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3821