Why is nothing said about profanity? Is it not the case that misuse of the gift of language is unholy? Does it not procede from uncleaness on the inside...and is it not considered a sin?

Maimonides in his Guide to the Perplexed (III 8), basing himself on Biblical and Talmudic sources, discusses at length the nobility of speech and urges the reader to refrain (as much as possible) from talking about food, physical desire and bodily functions. He adds that a sign of Hebrew being the Holy Language is that there are no Hebrew words for some of the things that should not be openly discussed.