http://revach.net/article.php?id=3127

Section: Daily Reminder   Category: Zechiras Miriam
Rabbeinu Yonah: Who Owns Your Lips?
Chazal tell us that someone who speaks Lashon Hara denies Hashem's existence.  Rabbeinu Yonah asks, why is this different than any other aveira that one commits?

He answers that we know that we are held accountable for every one of our actions.  We do aveiros because we cannot control ourselves.  But when it comes to speech we sometimes think that this a power given to us to do as we please, since it is just air.

"Sifaseinu Itanu Mi Adon Lanu" (Tehilim 12:5).  The Baal Lashon Hara says our lips are ours and their is no other boss over it, unlike our other limbs which belong to Hashem.  This is the attitude of a Kofer.

"Zachor Eis Asher Asa Hashem L'Miriam BaDerech B'Tzaischem MiMitzrayim"

The Ramban and other Rishonim count, among the Mitzvos Aseh Min HaTorah, the mitzva of remembering and saying with your mouth each day what Hashem did to Miriam when she spoke about her brother Moshe.  The Chofetz Chaim in Shaar Tvunah Perek 12 says that being Mikayem this mitzva can save you from the aveira of Lashon Hara.  More than just saying the pasuk, says the Chofetz Chaim, one must think about the incident in order for it to have its intended effect.
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