Nephi creates an aside that comments on the meaning of the final judgement predicted by Isaiah. There is little real difference between the two statements, with Nephi only more solidly linking the “meek of the earth” in Isaiah to “his people” in verse 30. The wicked are opposed to the meek/covenant people, and are destroyed. Nephi’s interjection of “by fire” is simply a reiteration of the cleansing fire of the final triumphant entry of the Savior, which has also been part of the Isaianic predictions.