Muslim sources accuse Jews living in Khaybar of a plan to unite with other Jews from Banu Wadi Qurra, Taima', Fadak as well as Ghatafan Arab tribe to attack Madinah. Scottish historian William Montgomery Watt notes the presence in Khaybar of the Banu Nadir, who were working with neighboring Arab tribes to protect themselves from the Islamic community in Medina who had earlier sent into exile the Jewish tribes for violating the terms of the Charter of Medina and for conspiring to kill Muhammad. Italian orientalist Laura Veccia Vaglieri claims other motives might have included the prestige the engagement would confer upon Muhammad among his followers, as well as the booty which could be used to supplement future campaigns.