At this point, Isaiah shifts from condemning Israel to providing hope. For Nephi, he would have likened this to his people after they had split from Laman and Lemuel. Nephi was part of the family while it suffered afflictions in their journey through the desert and across the ocean. Although we see a righteous Nephi, we also see a Nephi who suffered.
Jehovah says that Israel has been refined in the furnace of affliction. Nephi saw himself, and his people, as having been refined in the furnace of affliction.
The important declaration is that Jehovah is with Israel in Isaiah’s original meaning, but in Nephi’s likening, it is that Jehovah is with the Nephites. Jehovah declares himself and his power—and then the promise that he would fulfill his word.
When Isaiah says that Jehovah will “do his pleasure on Babylon,” it refers to the destruction of Babylon. For Nephi, it was protection against the Lamanites.
In the final verse of this section, Isaiah obliquely speaks of a prophet, indicating that “the lord hath loved him,” and that “he will fulfil his word.” This prophet becomes the subject of the next set of verses.