I say, and with God's guidance: Backbiting is forbidden, but it is permissible in the following cases:

1. Grievance: That is, complaining about someone's injustice to a ruler, saying: So-and-so has wronged me in such-and-such a way, so that he may be justly treated.
2. Consultation: Such as seeking advice regarding marriage, travel, partnership, residency, and depositing a trust, etc. It is permissible to mention what one knows with the intention of advising.
3. Pointing out a defect to someone who intends to buy something, mentioning it to the buyer. Similarly, if the buyer sees the seller giving counterfeit money, for example, he may say: Be cautious of him for such-and-such a reason.
4. Seeking a fatwa: By saying to the mufti, So-and-so has wronged me in such-and-such a way, and what is the way out? It is safer to say, What is your opinion about a man whose father, son, or someone else has wronged him in such-and-such a way? However, being explicit is permissible to this extent because the mufti may understand with specification what he would not understand with ambiguity.
5. With the intention of seeking help from someone who has the ability to admonish him.
6. For the purpose of identification: Such as being known by a nickname like the lame, the blind, or the one-eyed.
7. Critiquing the faults of the injured among narrators, witnesses, and authors is permissible, rather it is obligatory to protect the Sharia.
8. Mentioning the openly sinful: This refers to someone who does not conceal his actions and is not affected when it is said about him that he does such-and-such. It is permissible to mention him by what he openly does, but if he is concealing it, then backbiting him is not permissible.
9. Backbiting the unknown: There is no backbiting except for someone known. Even if the people of a village backbite, it is not considered backbiting because they do not intend all of them, but rather some of them, and that is unknown.
10. Mentioning the faults of a brother out of concern is not considered backbiting; rather, backbiting is when one mentions them out of anger intending to insult. If it reaches him, he would not dislike it because he is concerned for him, saddened, and regretful for him. However, it is conditioned that he is sincere in his concern; otherwise, he would be a hypocritical backbiter, praising himself because he insulted his Muslim brother and revealed what he concealed, making people feel that he dislikes this matter for himself and others, and that he is among the righteous since he did not explicitly engage in backbiting, but rather did so under the guise of concern, thus he has combined various types of evils. We ask God for protection.
11. Mentioning the wickedness of the obstinate: This refers to someone with a bad belief, like an innovator who conceals it and presents it to those who are caught by it. However, if he openly declares it, he falls under the openly sinful. Likewise, someone who prays and fasts but harms people. See: Al-Durr Al-Mukhtar and Rad Al-Mukhtar 6: 408.

And Ibn Abidin organized it in Rad Al-Mukhtar 8: 409, saying: "What a person dislikes is forbidden to mention except for ten cases that are permissible: Grievance, consultation, critique, and clarifying the openly sinful, the unknown, and deceit for the purpose of advising, and identifying such-and-such, seeking a fatwa, seeking help from an admonisher, and being concerned about the wickedness of the obstinate. And God knows best."