Sahih Muslim 49 a
It is narrated on the authority of Tariq b. Shihab:
It was Marwan who initiated (the practice) of delivering khutbah (address) before the prayer on the 'Id day. A man stood up and said: Prayer should precede khutbah. He (Marwan) remarked, This (practice) has been done away with. Upon this Abu Sa'id remarked: This man has performed (his duty) laid on him. I heard the Messenger of Allah as saying: He who amongst you sees something abominable should modify it with the help of his hand; and if he has not strength enough to do it, then he should do it with his tongue, and if he has not strength enough to do it, (even) then he should (abhor it) from his heart, and that is the least of faith.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، عَنْ سُفْيَانَ، ح وَحَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، كِلاَهُمَا عَنْ قَيْسِ بْنِ مُسْلِمٍ، عَنْ طَارِقِ بْنِ شِهَابٍ، - وَهَذَا حَدِيثُ أَبِي بَكْرٍ - قَالَ أَوَّلُ مَنْ بَدَأَ بِالْخُطْبَةِ يَوْمَ الْعِيدِ قَبْلَ الصَّلاَةِ مَرْوَانُ فَقَامَ إِلَيْهِ رَجُلٌ فَقَالَ الصَّلاَةُ قَبْلَ الْخُطْبَةِ ‏.‏ فَقَالَ قَدْ تُرِكَ مَا هُنَالِكَ ‏.‏ فَقَالَ أَبُو سَعِيدٍ أَمَّا هَذَا فَقَدْ قَضَى مَا عَلَيْهِ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏
"‏ مَنْ رَأَى مِنْكُمْ مُنْكَرًا فَلْيُغَيِّرْهُ بِيَدِهِ فَإِنْ لَمْ يَسْتَطِعْ فَبِلِسَانِهِ فَإِنْ لَمْ يَسْتَطِعْ فَبِقَلْبِهِ وَذَلِكَ أَضْعَفُ الإِيمَانِ ‏"‏ ‏.‏