Sefer Chofetz Chaim chapter 10 halacha 1

The topic of this chapter is whether or how one can speak lashon hara about someone who transgressed a mitzva between man and fellow man like stealing, denying a loan, causing injury, embarrassing, or causing pain to others and onaas devarim. If one knows someone else hurt or stole from the other then you should first rebuke the perpetrator and if he doesn’t listen and you know without a doubt that he did not do Teshuva which includes returning the stolen object, paying back damages, or apologizing for embarrassment etc. then you are allowed to tell others about what happened if it will help the victim get his money and to resolve the truth but there are 7 rules you must meet when you tell it to others.

There is an argument between Rabbeinu Yona and the Rambam (accept according to the Lechem Mishna) whether you can repeat what you saw a person do against his friend in all situations, as per the Rabbeinu Yona, or only in situations where money is involved i.e. stealing, physical injuries etc. but if it’s just a matter of psychological embarrassment and pain which just needs an apology then even if he doesn’t repent and ask for forgiveness the Rambam holds you can’t share what you saw with anyone else whereas Rabbienu Yona says you can for the sake of revealing the truth and making sure he doesn’t do this to anyone else. Keep people away from the perpetrator.

The fact that you have to know for a fact that he didn’t return money owed before speaking lashon hara is true by a normal Jew and especially a sage, you have to be sure to not talk up so quick because chaza”l say you can be assured if a sage sinned one day he has repented by the next day but if you know the money wasn’t paid back, even if the sage might feel remorse it’s not a complete Teshuva until payback so it’s lashon hara to spread what happened if it will get the perpetrator even a sage to pay back what is owed and keep people away from him until he fully repents