Musnad Ahmad 30:3730

'Ali narrated to us, Warqa' informed us, from Abu al-Zinad, from al-A'raj, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The Hour will not be established until you fight the Turks, [who have] small eyes, red faces, and flat noses, as if their faces are hammered shields."