Malik related to me that he heard that Umar ibn al-Khattab wantedto go to Iraq, and Kabal-Ahbar said to him, "Do not go there, amir al-muminin. There is nine-tenths of sorcery there and it is the place ofthe rebellious jinn and the disease which the doctors are unable tocure."
USC-MSA web (English) reference: Book 54, Hadith 30
Arabic reference: Book 54, Hadith 1795