Musar sobre I Reis 1:14

There are a few instance where it is commendable to engage in gossip. For example, in the case of two wicked men who have taken counsel to do evil, it is permitted, by gossip, to make them hate each other and do evil to one another, in order that they do not do evil to good people. And so is it with an adulterer who is pursuing an adultress, it is a good deed to gossip about them so that they should not commit the transgression. And there are times when even though the sinner is a completely wicked person it still is not proper to shame him in public — when there is the danger that this will cause him to become an unbeliever. It is permissible to use gossip against people who are always starting quarrels, as it is said, "I also will come in after thee, and confirm thy words" (I Kings 1:14) (See T.P. Peah 1:1).