In 3 Nephi 12:13 Jesus declares:
Verily, verily, I say unto you, I give unto you to be the salt of the earth; but if the salt shall lose its savor wherewith shall the earth be salted? The salt shall be thenceforth good for nothing, but to be cast out and to be trodden under foot of men.
Elder Carlos E. Asay explained that "salt will not lose its savor with age. Savor is lost through mixture and contamination. . . . Flavor and quality flee a man when he contaminates his mind with unclean thoughts, desecrates his mouth by speaking less than the truth, and misapplies his strength in performing evil acts." (Conference Reports, April 1980, p. 60) [Joseph F. McConkie, Robert L. Millet, Brent L. Top, Doctrinal Commentary on the Book of Mormon, Vol. IV, p. 70]