The Jewish laws that are most difficult to keep but are most commonly violated are the laws regarding improper speech or "lashon hara".
We are taught that the harm done by speech is even worse than the harm done by stealing or by harming someone financially. Lost or stolen money can be repaid, but the harm caused by speech can never be repaired.
There is a famous Chassidic tale that illustrates the danger of improper speech......
A man went about the community telling malicious lies about the rabbi. Later he realized the wrong he had done and felt remorse. He went to the rabbi and begged his forgiveness, saying he would do anything to make amends. The rabbi told the man "Take a feather pillow, cut it open and scatter the feathers to the winds."
The man thought this was a simple enough task and he did it gladly. When he returned to tell the rabbi that he had done what the rabbi requested, the rabbi said, "Now go and gather the feathers." The man replied that this task would be impossible because all the feathers were scattered in the wind. The rabbi continued to say that "you can no more make amends for the damage your words have done than you can recollect all the scattered feathers."
There is a mitzva in the Torah which states "thou shalt not go up and down as a tale-bearer among thy people (Vayikra 19:16). It is a violation in Jewish law to say anything about another person, even if it is true. The person who listens to tale-bearing is even worse than the person who tells it, because no harm could be done by gossip if there was no one to listen to it. It has been stated that lashon hara kills three people, the person who speaks it, the person who hears it and the person about whom it is told. (Talmud Arachin 15b).
In terms of my son, lashon hara is most relevant. Over Pesach, one of my daughters kept getting emails from different friends asking her if it was true that her brother is gay. The emails were too random and varied to be coincidence. When we returned home from Israel after Pesach, there were messages on our phone from people who we have not heard from in over a year. We finally decided to tell a family friend that our son is gay and she told us that she heard about it over the last few weeks.
After some investigation with our son we were able to piece the following chain of events together.
A female friend of our son was being asked incessantly by their mutual friend what the story was with my son and whether he is gay. The female friend asked permission if she could "out" him and he said it would be all right to confide in her. It appears that no sooner had this person heard the news, then she sent an email to whomever she knows who also knows my son.
Our sages compare a tale-bearer to a merchant. Not a merchant of goods, but a merchant of information. We live in the information age and those feathers are now scattered.