William Smith tells James Murdock that Joseph could not translate a sealed portion, testifies that Joseph was divinely assisted.
William Smith, interview by James Murdock, "The Mormons and Their Prophet," Connecticut Congregational Observer, July 3, 1841: 1
After this Joseph Smith was supernaturally assisted to read and to understand the inscription; and he was directed to translate a great part of it. The pages which he was not to translate were found to be sealed together, so that he did not even read them and learn their contents. With an assistant to correct his English, he translated so much of the inscription as now makes the book of Mormon.