1 Nephi 4:14-18
14 And now, when I, Nephi, had heard these words, I remembered the words of the Lord which he spake unto me in the wilderness, saying that: Inasmuch as thy seed shall keep my commandments, they shall prosper in the land of promise.
15 Yea, and I also thought that they could not keep the commandments of the Lord according to the law of Moses, save they should have the law.
16 And I also knew that the law was engraven upon the plates of brass.
17 And again, I knew that the Lord had delivered Laban into my hands for this cause—that I might obtain the records according to his commandments.
18 Therefore I did obey the voice of the Spirit, and took Laban by the hair of the head, and I smote off his head with his own sword.
Notwithstanding Nephi was “led by the Spirit,” he needed to be convinced that he must kill Laban. After he had done so, he apparently had no question about what he must do next.
In the mind of the ancient Israelites, there was an inseparable connection between physical and spiritual strength. Consequently, even some of the most intensely spiritual psalms (like 21 and 25) end with a promise of military invulnerability. The Old Testament is replete with the idea that the righteousness of the king brings military success and the wickedness of the king brings military defeat and captivity. In this story of Nephi’s overcoming impossible odds to defeat the commander of the Jewish armies, he gives the details that demonstrate that he is invulnerable because the Lord is with him. This also demonstrates that his claim to kingship is legitimate—not just his personal kingship, but the dynasty he was establishing.