After teaching the Nephites concerning his prophecy that he had "other sheep" that were not of the fold at Jerusalem, he then said to the Nephites: "And verily, verily, I say unto you that I have other sheep which are not of this land, neither of the land of Jerusalem . . . they of whom I speak are they who have not as yet heard my voice; neither have I at any time manifested myself unto them. But I have received a commandment of the Father that I shall go unto them . . . therefore I go to show myself unto them." (3 Nephi 16:1-3.)
In the next chapter he makes it clear that these "other sheep" not of the land of Jerusalem nor of the Americas are the lost tribes of Israel. Therefore, he says, ". . . now I go unto the Father, and also to show myself unto the lost tribes of Israel, for they are not lost unto the Father, for he knoweth whither he hath taken them." (3 Nephi 17:4.)
Earlier in the Book of Mormon (2 Nephi 29:11-14), the Lord promises that in the mouths of three great scriptural witnesses the divinity of Christ would be established. It is of interest to note that evidently the resurrected Jesus Christ appeared to all of the peoples who were to write these great scriptural witnesses. He appeared as a resurrected being to the Jews, from whom we get the Bible; he appeared as a resurrected being to the Nephites, from whom we get the Book of Mormon; and he promises here that he is going to appear as a resurrected being to the lost tribes of Israel, from whom shall come the third great scriptural witness.