Sahih Muslim, 6593

Rapporté par Abu Huraira : Le Messager d’Allah ﷺ a dit : « Savez-vous ce qu’est la médisance ? » Les Compagnons ont répondu : « Allah et Son Messager savent mieux. » Il a dit : « La médisance, c’est de parler de ton frère d’une manière qu’il n’aime pas. » On lui demanda : « Et si ce que je dis est vrai ? » Il répondit : « Si ce défaut est vraiment en lui, tu as médit de lui ; et s’il n’y est pas, tu l’as calomnié. »

Abu Huraira reported Allah's Messenger (ﷺ) as saying:Do you know what is backbiting? They (the Companions) said: Allah and His Messenger know best. Thereupon he (the Holy Prophet) said: Backbiting implies your talking about your brother in a manner which he does not like. It was said to him: What is your opinion about this that if I actually find (that failing) in my brother which I made a mention of? He said: If (that failing) is actually found (in him) what you assert, you in fact backbited him, and if that is not in him it is a slander