36863, True to the Faith, Profanity, 128
Profanity is disrespect or contempt for sacred things. It includes casual or irreverent use of the name of any member of the Godhead. It also includes any type of unclean or vulgar speech or behavior.
Always use the names of Heavenly Father, Jesus Christ, and the Holy Ghost with reverence and respect. Misusing their names is a sin. Profane, vulgar, or crude language or gestures, as well as immoral jokes, are offensive to the Lord and to others.
Foul language harms your spirit and degrades you. Do not let others influence you to use foul language. Instead, use clean language that uplifts and edifies others. Choose friends who use good language. Set an example that will encourage those around you to use clean language. If friends and acquaintances use profanity, good-naturedly encourage them to choose other words. If they persist, politely walk away or change the subject.
If you have developed the habit of swearing, you can break it. Begin by making a decision to change. Pray for help. If you are tempted to use profane language, keep quiet or say what you have to say in a different way.
Additional references: Leviticus 19:12; D&C 63:60-64
See also Modesty; Temptation