“Lashon ha-ra” literally means “bad tongue,” ie gossip. Buddhism views it quite seriously as an infringement of harmful speech, but I especially love this Hasidic story used to illustrate it in Joseph Telushkin’s Jewish Literacy. Here’s the first part of the entry:

The biblical commandment forbidding gossip is probably the most widely disobeyed of the 613 laws of the Torah. Leviticus 19:16 teaches: “Do not go about as a talebearer among your people.” This basic principle forbids saying anything negative about another person, even if it is true, unless the person to whom one is speaking or writing has a legitimate need for this information (for example, in submitting a reference for a job applicant).

In the Talmud, the rabbis greatly elaborated on this biblical verse, arguing that destroying another’s name is akin to murder (Arakhin 15b), and like murder, the deed is irrevocable. The impossibility of undoing the damage done by harmful gossip is underscored in a Hasidic tale about a man who went through his community slandering the rabbi. One day, feeling remorseful, he begged the rabbi for forgiveness, and indicated that he was willing to undergo any penance to make amends. The rabbi told him to take several feather pillows, cut them open, and scatter the feathers to the winds. The man did so, and returned to notify the rabbi that he had fulfilled his request. He was then told, “Now go and gather all the feathers.”

The man protested. “But that’s impossible.”

“Of course it is. And though you may sincerely regret the evil you have done and truly desire to correct it, it is as impossible to repair the damage done by your words as it will be to recover the feathers.”