Back-biting. A  statement made about someone in their absence that would displease that person if they were aware of it – a statement which is true about them.

Qurʾān sūrah (chapter) 49, ayah (line) 12 famously compares the action of ghībah to consuming the flesh of one’s dead brother. Sahih International translates: 

“... And do not spy or backbite each other. Would one of you like to eat the flesh of his brother when dead? You would detest it. ...(49:12)”

Ghībah is a very serious sin in Islam. It is haram (forbidden) both to commit back-biting and to listen to it. Ghībah is a sin that violates both Allah’s rights (haqq Allah) and man’s rights (haqq al-nas). Therefore, the sinner must secure the back-bitten person’s forgiveness, as well as make tawbah (repent to God), in order to expunge the sin.