Christian leaders, including Pope Gregory the Great (served 590-604), objected to Jewish ownership of Christian slaves, due to concerns about conversion to Judaism and the Talmudic mandate to circumcise slaves. The first prohibition of Jews owning Christian slaves was made by Constantine I in the 4th century. The prohibition was repeated by subsequent councils: Fourth Council of Orléans (541), Paris (633), Fourth Council of Toledo (633), the Synod of Szabolcs (1092) extended the prohibition to Hungary, Ghent (1112), Narbonne (1227), Béziers (1246). It was part of Saint Benedict's rule that Christian slaves were not to serve Jews.