Footnote 2 continued: The Chofetz Chaim proved from a gemara in Shevuos daf 31a combined with the Rambam (hilchos Sanhedrin 21:7) that even listening to lashon hara is forbidden since it might lead to accepting it as truth. So it’s logical to say that if the Torah definitely forbade accepting lashon hara then it also forbade what would lead to it which is just listening. The Gemara in Shavuos and the Rambam were talking about judges listening to statements by one party before the court case officially starts. If that’s a problem because they might accept the first aide as fact even if he will eventually hear the other side of the story, all the more so in any other situation of just listening where many times the person talked about doesn’t defend himself therefore it’s for sure forbidden because it is easier to accept what you hear. The Pirkei Di’Rebbe Eliezer warns that just sitting among those who speak lashon hara, no mention of accepting what you hear, you are considered wicked and one who hangs around slanderers, that means just by listening. Finally, the Sefer Chareidim says straight out in the negative mitzvah that have to do with one’s ears that just listening to lashon hara is prohibited by the Torah. You can’t get any clearer than that but the Chofetz Chaim says he must know this because of all that was quoted earlier.
Footnote 3: When a person is allowed to listen to lashon hara for a constructive purpose like to avoid future feuds then you have to have two things in mind:
1. If the person is speaking out of hatred you can’t listen to him because he won’t be careful the prerequisites of permissibly speaking lashon hara for a constructive purpose listed later on.
2. You can listen in only if he had already started to speak with others so that you aren’t the one placing a stumbling block in front of the blind.
Footnote 4: When it says that if you are in a position to help someone correct his ways then you can listen to lashon hara in order to investigate if it is really true or not that is only if there is an inkling of possible truth to the matter but if you feel there is no way the guy you are listening to is telling the truth you have no obligation to be cautious about what you heard to rebuke the would be wrong doer.