Musnad Ahmad 30:558

'Abd al-Razzaq narrated to us, Ma'mar informed us, from al-Zuhri, from Ibn al-Musayyib, 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 a people fight you who wear shoes made of hair, and their faces are like hammered shields."