Halacha 5: It is forbidden to accept rechilus as truth even from a person who is believable and a trusted confidant to you as if he is 2 witnesses in court who are always believed (lest contradicted by 2 other witnesses) if there is no constructive purpose in the future. This is because just as it is forbidden to speak lashon hara and rechilus it is forbidden to accept no matter how honest and trustworthy the speaker is. There is also a prohibition of placing a stumbling block in front of the blind as well. However, if one is allowed to listen to what this trusted honest man is saying, for example if there might be physical or monetary harm potentially coming his way which he can avoid, then not only can he take precautions as he does when anyone else says something, but he can actually believe the person since he trusts what he says. However, that does not now give permission to the listener to repeat what he heard to others, even to family members unless it will apply to them as well for the future. This type of person is also only believed if it was firsthand information but secondhand information he is not believed because he wasn’t allowed to believe the first person who told it to him. The proof that one is allowed to believe an entrusted honest person is from Pesachim 113b by the story of Tuvia, however even if he is an honest confidant if there is any way to judge the person in question favorably one must do so.
Halacha 6: When one can trust an honest confidant he has to be someone who you know is good, meaning you know for sure that it is in his nature is never to lie or exaggerate and you can always rely on him for anything that he says all the time as if he is two witnesses testifying in court and no one else will come to spell any doubts on what he said. However even if he is that trusted, and you can actually believe him that does not mean you can take actions against the subject in discussion to cause him a monetary loss or to G-D forbid hit him, or even to verbally accost him. The Torah doesn’t allow you to believe the listener in order to do inappropriate things. Now if you decide you conveniently believe this speaker like two witnesses in this instance of lashon hara or rechilus but you haven’t relied on him at other times, then that is absolutely forbidden because on the contrary the more you believe and decide the matter is true, the more you fall into the category of speaking lashon hara and rechilus.