It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Leave the Turks alone as long as they leave you alone, for those who will snatch from my Ummah the blessings that Allah has granted them will be none other than Banu Qanthura'."
Imam al-Tabarani (may Allah have mercy on him) said: "Only Marwan bin Salim narrated this hadith from al-A'mash, and Abd al-Majid bin Abd al-Aziz is alone in narrating it."
Hadith Referenceالمعجم الأوسط / باب الميم / 5634
Hadith Takhrij«أخرجه الطبراني فى «الكبير» برقم: 10389»