Careful with your words

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."
http://www.jewfaq.org/speech.htm