Having made one good effort, everyone but Nephi was ready to give up the assigned task. Nephi was forced to assert his leadership over his older brothers. He took a serious oath, “as the Lord liveth,” to complete their assignment before they return to their father (v. 15). The significance of this oath is shown by the Lord’s use of it to affirm to the three witnesses of the Book of Mormon that “[Joseph Smith] has translated the book, even that part which I have commanded him, and as your Lord and your God liveth it is true” (D&C 17:6).
In addition to the oath he had taken, Nephi comes up with an alternate plan, to purchase the plates with his father’s riches (v. 16). Perhaps this was one reason why the Lord had commanded Lehi to leave his riches behind. In his foreknowledge, the Lord was leaving Laban without excuse. Nephi then reasons with his brothers to further convince them of why their father had been commanded to flee out of the land (vv. 17–18). They had heard these reasons before, but it set the stage for the real purpose of their return, to get the plates. Nephi gives two purposes for the plates; to preserve for their children the language of their fathers, and to preserve the prophecies of all the holy prophets since the world began (vv. 19–20). His arguments were persuasive.