I've never thought of it before … but Lehi's great faith is demonstrated again in this chapter.
Obviously Sariah loved her sons and was concerned for them when they went back to Jerusalem to retrieve the plates. But she was also greatly concerned for her own welfare. We can only assume that if Jacob had been born, he was still very young. With all the sons back in Jerusalem, Lehi and the rest of his family were probably helpless, should danger greet them.
Why didn't Lehi simply send two of the sons and keep the other two with the rest of the family? Perhaps it was a strategic move on Lehi's part. He asked Laman and Lemuel to go back and get the plates, but they murmured. Next he asked Nephi to go along as if he were saying to him, "I know you'll get the job done because of your faith in God." Then, maybe he felt that Samuel could learn some things from Nephi and so he sent Sam along for the ride. If nothing else, perhaps Lehi had hoped that some of Nephi's faith would rub off on the rest of his sons.
Regardless of the reasons for sending off all his sons on this mission, Lehi did it in faith. He was taking a risk. If they did not return, the rest of the family could possibly die. But his faith was not weak. Lehi's faith was so strong, he was absolutely convinced that they would arrive at the promised land. He tells his wife, "I have obtained a land of promise, in the which things I do rejoice; yea, and I know that the Lord will deliver my sons out of the hands of Laban, and bring them down again unto us in the wilderness" (v. 5).
The chapter ends with a few thoughts about preservation. When you find something good, you want to hold on to it as long as you can … you want to preserve it. Joseph, although sold into Egypt by his brothers, was preserved by the Lord. The Lord knew Joseph was good. Joseph eventually prospered and was in a position to preserve his father and family. If it had not been for Joseph, the Israelite nation might never have been born. Even as Joseph preserved his father, so the brass plates allowed Lehi and his family to preserve the commandments of God and as the commandments were preserved and as Lehi's family obeyed them, they too were preserved.
Lehi vowed to preserve the plates. They would never be "dimmed" from un-use. He would search them and keep them bright so that they would be preserved for later generations. He would eventually pass them on to Nephi. Whether implied or stated explicitly, Nephi took upon the responsibility to keep the brass plates bright. This would be a command to all the descendents of Nephi.
What ought we to preserve? We should preserve our testimonies by sharing and fortifying them. We should preserve our families by holding FHE in our homes, reading the scriptures every day, holding family prayer, attending church as a family. We should preserve our covenants by partaking of the sacrament every week, returning to the temple regularly and keeping our covenants all the time. All these things are simple and small (Alma 37:6), but by regular maintenance we would bring about the salvation of our souls and our families'.