LEV516 Another area where a person would be obligated to reveal confidential information is a case in which refusing to divulge the information would cause harm to befall an individual. According to Jewish law (Shulchan Aruch, Choshen Mishpat 426:1), if an individual knows that people are plotting against a particular person and the person refuses to divulge that information, even if obtained confidentially, that person has violated the prohibition of standing by while a brother's blood has been spilled [this verse]. How much and how immediate must harm be in order to obligate a person to reveal a confidence is discussed by the modern decisors. ... The Chafetz Chaim (Sefer Shemirat Halashon, Hilchot Rechilut, chap. 9, examples 2 and 3) writes that when another person is about to enter a business partnership and you know information that the potential partner is untrustworthy and would ruin the other person financially, then you have an obligation to "gossip" and reveal the information, even if it was obtained in confidence, under the heading of "Thou shalt not stand by while thy brother's blood is being spilled" [this verse and see notes of the Chafetz Chaim were he discusses this]. Similarly, if two people are about to enter marriage and you possess information that were the potential spouse to know, he or she would end the marriage, you are obligated to tell the person. This is not a law granting permission to tell, but it is an obligation to reveal the information.