Shmiras Halashon (guarding the tongue) is a practice in Judaism that is said to promote the quality of life and help combat and reduce Lashon Hara (evil tongue). It is a part of Jewish ethics known as mussar. King David once said, "He who loves life and would like to see good days, let him guard his tongue from evil and his lips from speaking deceit."[1] King Solomon said, "Whoever guards his mouth and tongue guards himself from trouble."
The concepts and practice of Shmiras Halashon are found all through ancient Jewish writings, the modern practice was birthed and popularised by Rabbi Yisrael Meir Kagan (Chofetz Chaim).