Jacob has also seen the Atoning Messiah, making another point in common among the three men. The mention of Jacob apparently reminds Nephi of the Deuteronomic law of witnesses:
At the mouth of two witnesses, or three witnesses, shall he that is worthy of death be put to death; but at the mouth of one witness he shall not be put to death. (Deut. 17:6)
One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sinneth: at the mouth of two witnesses, or at the mouth of three witnesses, shall the matter be established. (Deut. 19:15)
This law allows for the establishment of fact with a minimum of two or three witnesses. Nephi sees Isaiah, Jacob, and himself as three witnesses testifying that the Messiah will come. Nephi knows, however, that Yahweh will provide even more witnesses.