As Laman and Lemuel murmured, Nephi said to his father,
...I will go and do the things which the Lord hath commanded, for I know that the Lord giveth no commandments unto the children of men, save he shall prepare a way for them that they may accomplish the thing which he commandeth them.When they arrived in Jerusalem, Laman was the first to go to Laban's house and ask for the plates. He was not only refused, but was cast out of Laban's house. Just as Laman and Lemuel were about to turn back to return to their family in the wilderness, Nephi reminded them of the promise or oath they made to their father that they would obtain the plates and that they would not return without them. He reminded them that it was part of God's plan for them to have the records and therefore it would be made possible.
1 Nephi 3:7
Successful in persuading them, Nephi led them back to Jerusalem to speak with Laban as a group. Along the way, they stopped by their home and brought with them all of their gold, silver, and other precious things. Laban, impressed by their goods, stole it all from them and chased them out of his house with his servants following to kill them. Once they were safely away from the city, Laman and Lemuel were angry with Nephi and began to beat Nephi and Sam with a stick.
Immediately, an angel appeared to them commanding them to stop and to return again to Jerusalem. They were told that Laban would be delivered to them. Even after the angel disappeared, Laman and Lemuel continued to murmur because they didn't understand how someone as mighty as Laban, with his command of fifty men, would be delivered into the hands of four young men.