Hadith: Whoever of you sees something evil, let him change it with his hand; and 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

عن أبي سعيد الخُدْريِّ رضي الله عنه قال: سمعت رسول الله صلى الله عليه وسلم يقول:
«‌مَنْ ‌رَأَى ‌مِنْكُمْ ‌مُنْكَرًا فَلْيُغَيِّرْهُ بِيَدِهِ، فَإِنْ لَمْ يَسْتَطِعْ فَبِلِسَانِهِ، فَإِنْ لَمْ يَسْتَطِعْ فَبِقَلْبِهِ، وَذَلِكَ أَضْعَفُ الْإِيمَانِ».
[صحيح] - [رواه مسلم] - [صحيح مسلم: 49]

Abu Sa‘īd al-Khudri (may Allah be pleased with him) reported: I heard the Messenger of Allah (may Allah's peace and blessings be upon him) say:
"Whoever of you sees something evil, let him change it with his hand; and 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."
[Authentic hadith] - [Narrated by Muslim] - [Sahih Muslim - 49]

Explanation

The Prophet (may Allah's peace and blessings be upon him) commands that evil deeds - they are everything prohibited by Allah and His Messenger - should be changed, according to one's ability. So, if one sees some evil deed, he should change it with his hand, if he has the ability to do so. If he is unable to do this, then he should change it with his tongue, by forbidding the one who commits it, demonstrating its harm to him, and guiding him to goodness instead of that evil. If he is unable to fulfill this level, then he should change it with his heart, by disliking that evil deed and determining to change it if he has the ability. Changing evil deeds with the heart is the lowest level of faith in this regard.

Benefits from the Hadith

1. This Hadīth is a key source in outlining the levels of changing evil deeds.
2. We are enjoined to adopt gradation in forbidding evil deeds, each according to his capacity and ability.
3. Forbidding evil deeds is a fundamental element in religion, and it does not cease to be due upon everyone. Rather, every Muslim is obligated in accordance with his ability.
4. Enjoining what is right and forbidding what is evil is one of the characteristics of faith, and faith increases and decreases.
5. For forbidding evil, it is required to know that the act in question is evil.
6. For changing something evil, it is required that this does not lead to greater evil.
7. Forbidding evil has certain etiquettes and requirements that should be learned by Muslims.
8. Forbidding evil needs a Shar‘i policy, knowledge, and insight.
9. The lack of disapproval of something evil within the heart is an indication of weak faith.