Musannaf Ibn Abi Shaybah 39733 — Reports on Taif

Abu Bakr bin Abi Zuhayr al-Thaqafi narrates from his father that he heard the Prophet (peace and blessings be upon him) delivering a sermon at al-Naba' or al-Nabawah, and al-Nabawah is part of al-Ta'if. He (peace and blessings be upon him) was saying in his sermon: "Soon you will distinguish the people of Paradise from the people of Hell, and your best people from your worst." The people said: "O Messenger of Allah (peace and blessings be upon him)! By what means?" He (peace and blessings be upon him) said: "By good praise and by bad praise. You are the witnesses of Allah on the earth."