Taking the king’s word literally (v. 15), they buried their weapons as a testimony to God, and they went one step farther. They covenanted with God to shed their own blood rather than shed the blood of their brethren (vv. 17–18). The sacredness of a covenant to these people will be verified as they keep this covenant.
Mormon wants us to learn two things at this point, as illustrated by “thus we see” (v. 19). First, standing for the truth was more important to them than losing their lives. To not follow a truth was a sin. Mormon’s conclusion was drawn from Alma 23:1–7, 16–18. The king had sent a proclamation to all the people asking them to protect the missionaries, and to forsake the wicked traditions of their fathers. Accepting this request had brought them to believe and know the truth.
The second conclusion was drawn from Alma 24:6–18, where the king asked the people to not stain their swords, but to bury them as a testimony to God. The wording of the second precept suggests that Mormon had not recorded his words as correctly as he wanted to so he rewrote the precept. While we cannot ascertain his actions for sure, we do know that the people buried their physical weapons in exchange for spiritual or internal peace. They were doing what their earthly and their heavenly King wanted them to do. A covenant is a two-way contract, and they were agreeing to his will, as they seemed to have learned from his Spirit.