“The Things Which They Did Utter Were Forbidden That There Should Not Any Man Write Them”

Joseph F. McConkie, Robert L. Millet
This was such a sacred manifestation, the content of these inspired utterances were of such a nature, that mortal language could not adequately capture the true meaning and intent. In this sense, things of the Spirit are, unspeakable“ (compare 3 Nephi 17:15-18).”

Doctrinal Commentary on the Book of Mormon, Vol. 4