Musnad Ahmad Hadith 9901

It is narrated from Abu Huraira (may Allah be pleased with him) that the Noble Prophet (ﷺ) asked the companions (may Allah be pleased with them), "Do you know what backbiting is?" The companions (may Allah be pleased with them) replied, "Allah and His Messenger (ﷺ) know best." The Noble Prophet (ﷺ) said, "Backbiting is that you mention about your brother something regarding a fault which is not in him." Someone asked, "Please tell us, if that fault is present in my brother which I mention in his absence, then what is the ruling?" The Noble Prophet (ﷺ) said, "If the fault you mention is present in him, then you have backbitten him, and if the fault you mention is not present in him, then you have slandered him."