The Torah decrees: “Lo yachel devaro” – Do not violate your word.  The word yachel relates to the word chalul – hollow.  A person must realize that his words are not empty and hollow, but rather they give rise to a certain spiritual reality.

If one speaks words of Torah and sanctity, he creates sacred angels who intercede on his behalf in the heavens.  If, however, one speaks words of frivolity and lightheadedness, not to mention lashon hara and gossip, then he creates destructive angels who operate against him, Heaven forbid.  ~ The Arizal Hakadosh zt”l from Torah Tavlin