Revelation given through Joseph Smith the Prophet to John Whitmer, at Fayette, New York, June 1829 (see the heading to section 14). The message is intimately and impressively personal in that the Lord tells of what was known only to John Whitmer and Himself. John Whitmer later became one of the Eight Witnesses to the Book of Mormon.
6 And now, behold, I say unto you, that the thing which will be of the most worth unto you will be to declare repentance unto this people, that you may bring souls unto me, that you may rest with them in the kingdom of my Father. Amen.