Backbiting (ghībah) and slander (namīmah) are major sins in Islam. They destroy relationships, erode trust, and reflect a heart lacking taqwa. Islam strictly forbids speaking ill of others behind their backs or spreading rumors that cause division.
Allah warns:
وَلَا يَغْتَب بَّعْضُكُم بَعْضًا ۚ أَيُحِبُّ أَحَدُكُمْ أَن يَأْكُلَ لَحْمَ أَخِيهِ مَيْتًۭا فَكَرِهْتُمُوهُ ۚ
"Do not backbite one another. Would any of you like to eat the flesh of his dead brother? You would hate it."
— Surah Al-Ḥujurāt (49:12)
The Prophet ﷺ said:
"إِنَّ مِنْ أَكْبَرِ الْكَبَائِرِ النَّمِيمَةُ وَقَتْلُ النَّفْسِ وَالشِّرْكُ بِاللَّهِ"
"Among the greatest sins are slander, murder, and associating others with Allah."
— Sahih al-Bukhari (6056)
Backbiting is saying something true about someone behind their back they would dislike. Slander is spreading lies. Both are destructive.
Umar ibn al-Khattab (RA) would warn his governors not only against injustice but also against gossip and mischief. Abu Hurairah (RA) would walk away from any gathering where people spoke negatively of others.
Purifying the tongue leads to purification of the heart — a key to Jannah.