Is someone who works in an unlawful profession considered to be openly committing a sin, thus making backbiting permissible, such as a seller of tobacco, alcohol, or drugs, or someone who works in an interest-based bank? Is backbiting permissible for anyone who commits an unlawful act?

The default ruling for backbiting is prohibition, based on the Almighty's saying: "And do not backbite each other." However, backbiting a person who openly commits sin is permissible, but only concerning what he publicizes. Ibn Taymiyyah was asked about the Hadith, "There is no backbiting for a transgressor," and he replied that this Hadith is not from the words of the Prophet, peace and blessings be upon him. Rather, it is from Al-Hasan Al-Basri, who said: "Do you shy away from mentioning a wicked person? Mention him with what is in him so that people may beware of him." Regarding another Hadith, "Whoever casts off the cloak of modesty, there is no backbiting for him," he clarified that backbiting is permissible in two situations:

The first is for someone who openly commits sins, immoral acts, and innovations. In this case, it is obligatory to denounce and condemn him so that people may beware of him. This is in contrast to someone who conceals his sins; he should be covered, and advised secretly.

The second is when seeking advice about a matter related to him, such as marriage or business dealings, and it is known that he is not suitable for that. In this case, his true condition must be revealed as a form of sincere advice, as the Prophet, peace and blessings be upon him, did with Fatimah bint Qays. This advice must be purely for the sake of Allah the Almighty, and not out of personal desire.

Therefore, one who publicizes his sins may be exposed, but one who conceals them should not be, though he may be mentioned to someone who can advise or reprimand him.