Is it forbidden to insult others, especially if they initiated it and provoked the person into insulting them, such as by insulting their height, obesity, or thinness?

A Muslim is required to refrain from slandering other Muslims. It is permissible for him to respond to insults in kind, without exaggeration or falsehood, such as saying "you dog" to someone who said it to him. However, it is not permissible to insult the attacker's parents, as they have not wronged him. The best course of action is forgiveness and forbearance. It is also advisable to avoid gatherings where insults and backbiting are prevalent.