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 the first to strip my Ummah of their dominion and of what Allah has granted them will be the Banu Qanturah."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10351