It is narrated from Sayyiduna Khuraym bin Fatik al-Asadi (may Allah be pleased with him), who was a Companion of the Messenger of Allah (peace and blessings be upon him), that he heard the Messenger of Allah (peace and blessings be upon him) say: "The people of Sham (Syria) are the whip of Allah in His land; through them He takes vengeance on whomever He wills among His servants. It is forbidden for their hypocrites to prevail over their believers, and they will not die except in grief and anxiety."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 4148