Musnad Ahmad 28:308

'Abd al-Rahman ibn Muhammad al-Muharibi narrated to us, al-Hasan ibn 'Amr narrated to us, from Abu al-Zubayr, from 'Abd Allah ibn 'Amr, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "When you see my nation fearing the oppressor, such that they do not say to him, 'You are an oppressor,' then farewell has been bid to them."