Upon the authority of Anas ibn Maalik who said that, the Messenger of Allaah ﷺ said:
"When I was taken up to the heavens, I passed by a people who had nails of copper who were scratching their faces and chests. So I said, 'Who are they, O Jibreel?' He responded, 'They are the ones who eat the people's flesh (backbite) and transgress upon the honor of the people.'"
[This narration is authentic.]
Al Haafidh Ibn Katheer said in explanation of this: "And backbiting is prohibited by consensus. Nothing is exempted from this prohibition except whatever contains benefit, which is greater than its harm like (the science of), criticism, and appraisal Jarh wa Ta'deel), and advice, like his statement ﷺ when his permission was sought by that sinful man who desired to enter upon him: "Grant him permission, but what a wretched brother of his tribe." Additionally, like his statement ﷺ to Fatima bint Qays (radiallahu anha) when she received marriage proposals from Mu'aawiyyah and Abul-Jahm. He ﷺ said, "As for Mu'aawiyyah, then he is a poor man having no property; and as for Abul-Jahm, then he does not remove his staff from his shoulder." Similarly whatever follows along these same lines (is an exception) and whatever transgresses beyond that is the subject of extreme prohibition."
I say that the exceptional situations surrounding backbiting are gathered together in the statement of the poet:
"𝑻𝒉𝒆𝒓𝒆 𝒊𝒔 𝒏𝒐 𝒔𝒊𝒏 𝒊𝒏 𝒃𝒂𝒄𝒌𝒃𝒊𝒕𝒊𝒏𝒈 𝒊𝒏 𝒔𝒊𝒙 𝒔𝒊𝒕𝒖𝒂𝒕𝒊𝒐𝒏𝒔: 𝑪𝒐𝒎𝒑𝒍𝒂𝒊𝒏𝒊𝒏𝒈, 𝑰𝒅𝒆𝒏𝒕𝒊𝒇𝒚𝒊𝒏𝒈, 𝑾𝒂𝒓𝒏𝒊𝒏𝒈, 𝒂𝒏𝒅 𝒕𝒉𝒆 𝒐𝒏𝒆 𝒘𝒉𝒐 𝑶𝒑𝒆𝒏𝒍𝒚 𝑺𝒊𝒏𝒔, 𝒂𝒏𝒅 𝒖𝒑𝒐𝒏 𝑰𝒏𝒒𝒖𝒊𝒓𝒚, 𝒂𝒏𝒅 𝒇𝒐𝒓 𝒕𝒉𝒆 𝑶𝒏𝒆 𝑾𝒉𝒐 𝑹𝒆𝒒𝒖𝒆𝒔𝒕𝒔 𝑯𝒆𝒍𝒑 𝒊𝒏 𝑹𝒆𝒎𝒐𝒗𝒊𝒏𝒈 𝑬𝒗𝒊𝒍."These two lines of poetry are found in Subul as- Salaam [#1584]
Book: My Advice to the Women By the Shaykhah Umm 'Abdillaah al-Waadi'yyah
Translated by Abul Layth
Tarbiyyah Bookstore Publishing
P. 36, 37