Jacob builds on his theme of contrasting parallels. The first parallel contrasted righteous (in keeping this commandment) Lamanites with unrighteous (in keeping this commandment) Nephites. In this verse, he creates another implicit antithetical parallel: Because of their righteous observance of monogamy and fidelity, the Lamanites will not be destroyed. The implication is clear: Because the Nephites do not observe this commandment, they will be destroyed.
This prophecy is actually fulfilled over the next several generations, leaving only a remnant of Nephites to escape to Zarahemla while the Lamanites prosper (Omni 1:12–13). Again, even though this passage is frequently read as referring to the final battle, it seems to apply more directly to closer events.