The Jews have no right to enter the Arabian Peninsula
Question

                It is said that the Jew Labeed ibn al-A’sam was able to able to obtain something from the Prophet (peace and blessings of Allaah be upon him) [for the purpose of witchcraft] by the help of a Jewish slave woman who used to enter the houses of the Prophet (peace and blessings of Allaah be upon him). Does this mean that it is permissible to employ the services of Jews? 

What is the meaning of the expulsion of the Jews as narrated in the ahaadeeth? I hope that you could explain the presence of the Jews in Madeenah, as it is narrated that the Prophet (peace and blessings of Allaah be upon him) expelled them from the city?
Praise be to Allah.
    The Prophet  (peace and blessings of Allaah be upon him) 
    commanded that the Jews be expelled from the Arabian Peninsula, and said 
    that no two religions should co-exist in the Arabian Peninsula. This is a 
    shar’i ruling. It is not permissible for any mushrik to remain there. With 
    regard to the presence of the Jews in Madeenah, Khaybar, etc., this was 
    before the command to expel them, as is well known. The command to expel 
    them came during the final illness of the Prophet  (peace and blessings 
    of Allaah be upon him), then ‘Umar (may Allaah be pleased with him) expelled 
    them after that.