Whoever sees vice should change it with his hand, tongue, or heart

[Roohi]

Tariq ibn Shihab said: The first to begin the sermon on the Day of Eid before prayer was Marwan. A man stood and said, “Prayer comes before the sermon.” Marwan said, “This has been done away.” Abu Sa’id remarked: This man has done his duty. I heard the Messenger of Allah صلى الله عليه وسلم say, “Whoever sees vice, let him change it with his hand; and if he is unable, then with his tongue; and if he is unable, then with his heart, and that is the weakest (level of) faith.”



[Sahih Muslim, Book 1, Number 79]
Book of Faith, Chapter: Explanation that forbidding vice is part of Faith, and that Faith increases and decreases.

عَنْ طَارِقِ بْنِ شِهَابٍ وَهَذَا حَدِيثُ أَبِي بَكْرٍ قَالَ أَوَّلُ مَنْ بَدَأَ بِالْخُطْبَةِ يَوْمَ الْعِيدِ قَبْلَ الصَّلَاةِ مَرْوَانُ فَقَامَ إِلَيْهِ رَجُلٌ فَقَالَ الصَّلَاةُ قَبْلَ الْخُطْبَةِ فَقَالَ قَدْ تُرِكَ مَا هُنَالِكَ فَقَالَ أَبُو سَعِيدٍ أَمَّا هَذَا فَقَدْ قَضَى مَا عَلَيْهِ سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ مَنْ رَأَى مِنْكُمْ مُنْكَرًا فَلْيُغَيِّرْهُ بِيَدِهِ فَإِنْ لَمْ يَسْتَطِعْ فَبِلِسَانِهِ فَإِنْ لَمْ يَسْتَطِعْ فَبِقَلْبِهِ وَذَلِكَ أَضْعَفُ الْإِيمَانِ
كِتَاب الْإِيمَانِ – باب بَيَانِ أن النَّهْيِ عَنْ الْمُنْكَرِ مِنْ الْإِيمَانِ وَأَنَّ الْإِيمَانَ يَزِيدُ وَيَنْقُصُ