David Marks reports as hearing that only Joseph could translate the BOM.
David Marks, The Life of David Marks, To the 26th year of his age. Including The Particulars of His Conversion, Call to the Ministry, and Labours in Itinerant Preaching For Nearly Eleven Years (Limerick Maine: Office of the Morning Star, 1831), 340
They stated the writing could be read by no person, except by the said Smith; and, that the Lord had inspired him to translate and publish the book,—that none, but twelve chosen witnesses, had been allowed to see these plates, and that now they were "hid up unto the Lord."