Musnad Ahmad 1017:17

Abu Nu'aym narrated to us, Bashir ibn al-Muhajir narrated to us, 'Abdullah ibn Buraydah narrated to me, from his father, who said: I was sitting with the Prophet, peace and blessings of Allah be upon him, and I heard the Prophet, peace and blessings of Allah be upon him, say: "My nation will be driven by a people with broad faces and small eyes, as if their faces are leather shields, three times, until they overtake them in the Arabian Peninsula. As for the first driving, those who flee from them will be saved. As for the second, some will perish and some will be saved. As for the third, they will all be wiped out, whoever remains of them." They said: "O Prophet of Allah, who are they?" He said: "They are the Turks." He said: "By the One in Whose hand is my soul, they will surely tie their horses to the pillars of the Muslims' mosques." He said: And Buraydah would never be without two or three camels, travel provisions, and water skins, preparing for the flight due to the affliction he heard from the Prophet, peace and blessings of Allah be upon him, regarding the matter of the Turks.