Musnad Ahmad 1034:76

Abu Dawud narrated to us, Hisham narrated to us, from Qatadah, from Abu al-Tufayl, who said: I and ‘Amr ibn Sulay‘ set out until we came to Hudhayfah. He said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "Indeed, this tribe of Mudar will not leave a single righteous servant of Allah on the earth without putting him to trial and destroying him, until Allah overtakes them with soldiers from Himself, so He will humiliate them until they cannot even defend the tail of a hill."