Notice that the Spirit had commanded Nephi three different times to slay General Laban. The Spirit had even explained to Nephi why God was justified in commanding Laban to be slain. Still Nephi hesitated. He began to reason within himself. As he later wrote:
“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. 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. And I also knew that the law was engraven upon the plates of brass. 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. 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.”