Musnad Ahmad 66:1

'Abd al-Malik ibn 'Amr and Surayj—the meaning is the same—said: Nafi' ibn 'Umar narrated to us, from Umayyah ibn Safwan, from Abu Bakr ibn Abi Zuhayr—both of them said: from Abu Bakr ibn Abi Zuhayr al-Thaqafi—from his father, who said: I heard the Prophet, peace and blessings of Allah be upon him, saying at al-Naba'ah—or al-Nabawah, Nafi' was uncertain—from al-Ta'if, and he was saying: "O people, you are about to know the people of Paradise from the people of the Fire—or he said: your best from your worst." He said: A man from the people said: "By what, O Messenger of Allah?" He said: "By evil praise and good praise, and you are the witnesses of Allah, some of you over others."