Musnad Ahmad 31:875

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from Qays ibn Muslim, from Tariq ibn Shihab, that Marwan delivered a sermon before the prayer. A man said to him, "The prayer is before the sermon." Marwan said to him, "That has been abandoned, O Abu so-and-so." Abu Sa‘id said, "As for this one, he has fulfilled what was upon him. The Messenger of Allah, peace and blessings of Allah be upon him, said to us: 'Whoever among you sees an evil, let him change it with his hand; if he is not able, then with his tongue; and if he is not able, then with his heart, and that is the weakest of faith.'"