Sefer Chofetz Chaim hilchos rechilus chapter 5 halachos 1-2

Just as it is forbidden to accept lashon hara as truth it is also forbidden to accept rechilus as truth. It comes from the same prohibition, “לא תשא שומע שוא” (Shemos 23:1). The Chofetz Chaim goes into great detail proving that the term lashon hara is inclusive or interchangeable with rechilus though rechilus never refers to lashon hara. There are other possible prohibition and breaking of positive mitzvos involved in accepting rechilus as truth in one’s heart which were discussed in the introduction of Sefer Chofetz Chaim. Chazal in Erichin 15b and a gemara Yerushalmi Peah 1:1 both say that there are 3 people who could be killed potentially when lashon hara is spoken the speaker, acceptor and victim that was talked about. We saw this when Doeg spoke rechilus about the City of Nov who was hiding David and he told jealous King Shaul they were hiding him. Doeg was killed, the whole city of Nov was wiped out, and King Shaul was eventually ruthlessly killed in battle. The one who accepts lashon hara is worse than speaking it. Also, the gemara in Pesachim 118a says that whoever’s speaks or accepts lashon hara as truth deserves to be thrown to the dogs, as we see that right after the pasuk prohibiting accepting lashon hara it says and it will be thrown to the dogs. The simple understanding of that verse is that any meat improperly slaughtered should be thrown to the dogs because it is not kosher. But the gemara made a drasha from the juxtaposition of verses that those who speak and accept lashon hara deserve to be thrown to the dogs. Even listening is forbidden (because you can’t give credence to lashon hara) this means you can’t sit down in a group of lashon hara talkers and say I won’t accept what they say without researching, I’ll just listen. But certainly accepting rechilus or lashon hara as truth without researching the matter is worse and always forbidden, whereas at times just listening and looking into the matter might be mitzvah if it’s a matter which might affect you physically, or monetarily in a negative way and you have a mitzvah to take proper precautions. It’s a very hard balance to figure out when you can and can’t listen but that’s part if our service of Hashem and according to our efforts is our reward.