In the early days of Islam, Muhammad offered to spare the lives of the sa'alik if they converted, and allowed them to keep their stolen booty. They served as mercenaries during the First Fitna, particularly in the Battle of the Camel. They flourished as bandits during the Umayyad Caliphate, but under the Abbasid Caliphate their composition seems to have shifted. They became "quasi-military units composed of Arabs