What is the ruling on quarreling and insulting among Muslims?

Muslims, if they differ, must resort to the Sharia for judgment. Conflict and fighting are forbidden, except in the case of aggression, where the one aggressed upon has the right to defend himself. The use of vulgar language in jest is forbidden, and if it includes slander or violation of sacred limits, it is even more forbidden. Those who do so must be advised, and if they do not desist, one must distance himself from their company.