What does the Quran say about backbiting?

Yes, the Quran forbids backbiting (ghibah) very clearly. It compares it to eating the flesh of your dead brother, an image meant to show how ugly it is to talk behind someone's back. The Prophet ﷺ explained that backbiting means speaking about a person in a way they would dislike, even if what you say is true.

The famous image in Surah al-Hujurat

The main verse comes after Allah tells believers to avoid suspicion and spying. It then says:

وَلَا تَجَسَّسُوا۟ وَلَا يَغْتَب بَّعْضُكُم بَعْضًا ۚ أَيُحِبُّ أَحَدُكُمْ أَن يَأْكُلَ لَحْمَ أَخِيهِ مَيْتًا فَكَرِهْتُمُوهُ "And do not spy, nor backbite one another. Would any of you like to eat the flesh of their dead brother? You would despise that!" Quran 49:12

The picture is powerful. A dead person cannot defend himself, and a person who is being talked about behind his back cannot either. The verse ends with a call to fear Allah, "the Accepter of Repentance, Most Merciful", so there is always a way back.

What counts as backbiting?

The Companions were asked this by the Prophet ﷺ, and he answered: "Your talking about your brother in a manner which he does not like." When asked what if the fault is really in him, he replied that if it is, you have backbitten him, and if it is not, you have slandered him (Sahih Muslim 2589). So truth is not an excuse. Examples include:

Mocking someone's looks, accent, family or habits when they are not there.
Sharing someone's private mistakes or struggles for entertainment.
Group chat or social media comments that run someone down.

Backbiting is just as real in writing as in speech, because posts and messages can be seen by many people. See Is it backbiting to complain about someone online?

Related warnings

The Quran also says "Woe to every backbiter, slanderer" (Quran 104:1), and tells believers not to ridicule one another or call each other offensive names (Quran 49:11). It teaches us to "say what is right" (Quran 33:70). The Prophet ﷺ taught that whoever believes in Allah and the Last Day should speak what is good or keep quiet (Sahih al-Bukhari 6018). See What does the Quran say about lying?

When speaking about someone is allowed

Scholars list a few cases where it is not sinful to mention someone's fault: asking a judge or authority to stop an injustice, asking a scholar for a ruling, or warning others of real harm, such as a fraud or an unsafe person. The aim must be to help or protect, not to enjoy talking about someone.

If you have backbitten

Stop, ask Allah for forgiveness and resolve not to repeat it. If it is safe and will not cause more harm, you can apologise to the person. Otherwise, speak well of them and make dua for them. See What does the Quran say about forgiveness?

Key points

Quran 49:12 compares backbiting to eating your dead brother's flesh.
Backbiting is saying what a person would dislike, even if it is true.
Saying something false about them is slander, which is worse.
Warning about real harm or seeking justice is an allowed exception.

Tip: When a conversation turns to gossip, change the subject or say something kind about the person. Even this small step protects your tongue and the absent person.