Jacob taught with power and authority from God. He was “called of God, and ordained after the manner of his holy order” (received the holy priesthood) and “consecrated” (or set apart) by his brother Nephi (2 Nephi 6:2; see also 2 Nephi 5:26). In addition, Jacob employed three important elements of effective teaching, as explained by Elder Jeffrey R. Holland of the Quorum of the Twelve Apostles: “‘For I have exhorted you with all diligence; and I have taught you the words of my father; and I have spoken unto you concerning all things which are written, from the creation of the world’ [2 Nephi 6:3; italics added]. That is the formula by which the gospel has always been taught, a process used to this day—personal testimony, the teachings of the living prophets, and the written record of the scriptures” (Christ and the New Covenant [1997], 65).
President Joseph Fielding Smith explained what “order” of the priesthood the Nephites exercised: “The Nephites were descendants of Joseph. Lehi discovered this when reading the brass plates. … Therefore there were no Levites who accompanied Lehi to the Western Hemisphere. Under these conditions the Nephites officiated by virtue of the Melchizedek Priesthood from the days of Lehi to the days of the appearance of our Savior among them” (Answers to Gospel Questions, 1:124).