Illustrations paragraph 3
3. Furthermore, Levi must be very careful not to advise Reuven to make a partnership with Shimon if he knows that harm can result, for example, if Shimon is poor or dishonest. The same applies if Levi is asked about Shimon regarding marriage or work. For the whole prohibition of rechilus is to cause harm to Shimon. But to do the opposite and harm Reuven by telling him to make a partnership etc. with Shimon in circumstances where Levi himself would avoid Shimon, counts as, Do not put a stumbling block before the blind, which, the sages say, means “that one should not give him unsuitable advice.” Some people transgress this because of personal gain. This is a serious transgression – love of money causes people to transgress a Torah prohibition.