According to Bruce Van Orden, in the midst of Moroni's challenge to readers of the Book of Mormon to exercise faith and build trust in Jesus Christ, Moroni cited a statement the Lord made to his disciples when he visited them in the New World:
Go ye into all the world, and preach the gospel to every creature; And he that believeth and is baptized shall be saved, but he that believeth not shall be damned; And these signs shall follow them that believe . . . (Mormon 9:22-24)
We otherwise do not have this full statement in the Book of Mormon, although the concept of believing and being baptized is in 3 Nephi 11:33-34. . .
We may note that Jesus' statement to his Nephite disciples mirrors almost exactly what he said to his Jerusalem apostles following his resurrection when he met with them in the Upper Room as recorded in Mark 16:15-17. Many biblical scholars, noting that the text of Mark 16:9-20 was not found in the earliest extant manuscripts, have concluded that these verses were added to the text in the second century by an editor named Aristion (or Ariston) and that these passages are therefore not "Markan" (Interpreter's Bible 7:915-16). But the Book of Mormon confirms that the Lord indeed taught these principles. It undoubtedly parallels what the Savior taught in the Old World. We also have a briefer account of these teachings the Lord gave to Moroni as he abridged the Jaredite record (Ether 4:18). Thus the Book of Mormon has two witnesses of Jesus' teachings recorded in Mark. This is yet another instance wherein the Book of Mormon text verifies the legitimacy of the biblical text. [Bruce A. Van Orden, "Preach the Gospel to Every Creature," in The Book of Mormon: Fourth Nephi through Moroni, From Zion to Destruction, pp. 324-325]