Today we covered Negative Mitzvos 7-9 in the prologue.
Negative mitzvah 7: ״לא תשנא את אחיך בלבביך״ “Do not hate your brother in your heart.” If a person is nice to someone to his face but speaks loshon hara about him to others, The Chofetz Chaim says this sin is so severe and is even specified in the Torah because it is worse than regular hatred since the one being hated cannot defend himself. If one lashes out, out of hatred against someone he can physically or verbally defend himself but if the enemy is speaking peace to your face and hurts you behind your back what can you do? This sin only applies to the one speaking loshon hara and only as long it is behind the back of the guy he is speaking about.
The 8th and 9th negative mitzvos are ״לא תקום ולא תטור״ “Don’t take revenge or bear a grudge.” If someone did something bad to you and you remember it and then speak loshon hara about him so that other people won’t act kindly towards him, this is bearing a grudge and taking revenge. One should just forget about anything bad one does to you. The Sefer HaChinuch and Rambam both hold that not taking revenge or bearing a grudge applies whether someone did something against you monetarily, physically, or verbally. The Sefer HaChinuch’s advice to forgive and forget is that really everything is from Hashem and this person is just a messenger to cause harm to you in order to atone for a sin you have done so you can’t take revenge or bear a grudge against him since he really did nothing wrong it is your sin which brought the harm upon you. However the Chofetz Chaim adds that at the time of being harmed one is allowed to defend himself however it is a positive trait to overlook any bad one says about you or even does to you, unless physically defending your self from getting harmed. Otherwise after the fact it is forbidden to care about what happened because that will be bearing a grudge which could lead also to revenge. These sins could apply to both the speaker and listener of lashon hara, for if the listener adds his input or agrees fully what the speaker says because he was wronged by the same guy then he is transgressing taking bearing a grudge and or taking revenge.