The most sublime words written on this topic were penned by the apostle James, who wrote:
'If any man offend not in word, the same is a perfect man, and able also to bridle the whole body….
Even so the tongue is a little member, and boasteth great things. Behold, how great a matter a little fire kindleth!…
But the tongue can no man tame; it is an unruly evil, full of deadly poison….
Out of the same mouth proceedeth blessing and cursing. My brethren, these things ought not so to be.
Doth a fountain send forth at the same place sweet water and bitter?' (James 3:2-11)
Gordon B. Hinckley
"I say this to the boys. I say it also to any of you older men. . . . I do so with love…I know that the Lord is pleased when we use clean and virtuous language, for He has set an example for us. His revelations are couched in words that are affirmative, that are uplifting, that encourage us to do what is right and to go forward in truth and goodness.
"Don't swear. Don't profane. Avoid so-called dirty jokes. Stay away from conversation that is sprinkled with foul and filthy words. You will be happier if you do so, and your example will give strength to others." (Church News, Mar. 23, 1996, "A Thought From the Scriptures.")
"Many of our boys who [play] in the streets and use profane language, know not what they are doing, but there are old men, members of the High Priests' Quorum, and of the High Council, who, when they get into a difficulty in the [canyon] and are perplexed, will get angry and swear at, and curse everything around them. I will insure that I can find High Priests who conduct in this manner. But on their way home their feelings become mollified, and they wish to plead with the Lord to forgive them. Could you place yourselves in some of our [canyons], or in some other difficult places, out of sight but within hearing, and hear some of the brethren curse and swear at their cattle and horses, you would not have the least idea that they had ever known anything about 'Mormonism,' but follow them home and you may find them pleading with the Lord for pardon. There are just such characters in our midst." (Journal of Discourses, vol. 3, p. 275)