When non-observant people talk about how difficult it is to observe Jewish law, they usually mention the difficulty of observing Shabbat or keeping kosher or other similarly detailed rituals. Yet the laws that are most difficult to keep, that are most commonly violated even by observant Jews, are the laws regarding improper speech. This is a very important area of Jewish law; entire books have been written on the subject.
Judaism is intensely aware of the power of speech and of the harm that can be done through speech. The rabbis note that the universe itself was created through speech. Of the 43 sins enumerated in the Al Cheit confession recited on Yom Kippur, 11 are sins committed through speech. The Talmud tells that the tongue is an instrument so dangerous that it must be kept hidden from view, behind two protective walls (the mouth and teeth) to prevent its misuse.
The harm done by speech is even worse than the harm done by stealing or by cheating someone financially: money lost can be repaid, but the harm done by speech can never be repaired. For this reason, some sources indicate that there is no forgiveness for lashon ha-ra (disparaging speech). This is probably hyperbole, but it illustrates the seriousness of improper speech. A Chasidic tale vividly 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 began to feel remorse. He went to the rabbi and begged his forgiveness, saying he would do anything he could 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 strange request, but it was a simple enough task, and he did it gladly. When he returned to tell the rabbi that he had done it, the rabbi said, "Now, go and gather the feathers. Because you can no more make amends for the damage your words have done than you can recollect the feathers."
Speech has been compared to an arrow: once the words are released, like an arrow, they cannot be recalled, the harm they do cannot be stopped, and the harm they do cannot always be predicted, for words like arrows often go astray.
There are two mitzvot in the Torah that specifically address improper speech: Thou shalt not go up and down as a tale-bearer among thy people (Lev. 19:16), and ye shall not wrong one another (Lev. 25:17, which according to tradition refers to wronging a person with speech).
Tale-bearing is, essentially, any gossip. The Hebrew word for tale-bearer is "rakhil" (Reish-Kaf-Yod-Lamed), which is related to a word meaning trader or merchant. The idea is that a tale-bearer is like a merchant, but he deals in information instead of goods. In our modern "Information Age," the idea of information as a product has become more clear than ever before, yet it is present even here in the Torah.
It is a violation of this mitzvah to say anything about another person, even it is true, even if it is not negative, even if it is not secret, even if it hurts no one, even if the person himself would tell the same thing if asked! It is said that the telling of gossip leads to bloodshed, which is why the next words in the Torah are "you shall not stand aside while your fellow's blood is shed." The story of Do'eig the Edomite (I Samuel Chs. 21-22) is often used to illustrate the harm that can be done by tale-bearing. Do'eig saw Achimelekh the Kohein give David bread and a sword, a completely innocent act intended to aid a leading member of Saul's court. Do'eig reported this to Saul. Do'eig's story was completely true, not negative, not secret, and Achimelekh would have told Saul exactly the same thing if asked (in fact, he did so later). Yet Saul misinterpreted this tale as proof that Achimelekh was supporting David in a rebellion, and proceeded to slaughter all but one of the kohanim at Nob.
The person who listens to gossip is even worse than the person who tells it, because no harm could be done by gossip if no one listened to it. It has been said that lashon ha-ra (disparaging speech) kills three: the person who speaks it, the person who hears it, and the person about whom it is told. (Talmud Arachin 15b).
In Jewish law, all things are considered to be secret unless a person specifically says otherwise. For this reason, you will note that in the Torah, G-d constantly says to Moses, "Speak to the Children of Israel, saying:" or "Speak to the Children of Israel and tell them:" If G-d did not specifically say this to Moses, Moses would be forbidden to repeat his words! Nor is there any time-limit on secrets. The Talmud tells the story of a student who revealed a secret that he had heard 22 years earlier, and he was immediately banished from the house of study! (Talmud Sanhedrin 31a)
The gravest of these sins of tale-bearing is lashon ha-ra (literally, "the evil tongue"), which involves discrediting a person or saying negative things about a person, even if those negative things are true. Indeed, true statements are even more damaging than false ones, because you can't defend yourself by disproving the negative statement if it's true! Some sources indicate that lashon ha-ra is equal in seriousness to murder, idol worship, and incest/adultery (the only three sins that you may not violate even to save a life).
It is forbidden to even imply or suggest negative things about a person. It is forbidden to say negative things about a person, even in jest. It is likewise considered a "shade of lashon ha-ra" to say positive things about a person in the presence of his enemies, because this will encourage his enemies to say negative things to contradict you!
One who tells disparaging things that are false is referred to as a motzi sheim ra, that is, one who spreads a bad report. This is considered the lowest of the low.
It is generally not a sin to repeat things that have been told "in the presence of three persons." The idea is that if it is told in the presence of three persons, it is already public knowledge, and no harm can come of retelling it. However, even in this case, you should not repeat it if you know you will be spreading the gossip further.
There are a few exceptional circumstances when tale-bearing is allowed, or even required. Most notably, tale-bearing is required in a Jewish court of law, because it is a mitzvah to give testimony and that mitzvah overrides the general prohibition against tale-bearing. Thus, a person is required to reveal information, even if it is something that was explicitly told in confidence, even if it will harm a person, in a Jewish court of law.
A person is also required to reveal information to protect a person from immediate, serious harm. For example, if a person hears that others are plotting to kill someone, he is required to reveal this information. That is another reason why the commandment not to go about as a tale-bearer is juxtaposed with "you shall not stand aside while your fellow's blood is shed."
In limited circumstances, one is also permitted to reveal information if someone is entering into a relationship that he would not enter if he knew certain information. For example, it may be permissible to tell a person that his prospective business partner is untrustworthy, or that a prospective spouse has a disease. This exception is subject to significant and complex limitations; however, if those limitations are satisfied, the person with the information is required to reveal it.
In all of these exceptions, a person is not permitted to reveal information if the same objective could be fulfilled without revealing information. For example, if you could talk a person out of marrying for reasons other than the disease, you may not reveal the disease.
Leviticus 25:17 says, "You shall not wrong one another." This has traditionally been interpreted as wronging a person with speech. It includes any statement that will embarrass, insult or deceive a person, or cause a person emotional pain or distress.
Here are some commonly-used examples of behavior that is forbidden by this mitzvah: