At the end of the previous verse, Isaiah introduces himself as Jehovah’s messenger. These verses begin to define the reason why Jehovah has selected him. In Nephi’s likening, he would have seen himself in these verses.
Through Isaiah, Jehovah would be glorified as Isaiah communicated God’s will. Nephi similarly glorified Jehovah as he taught his people. Nephi may have thought this even more important in his case, as it is probable that his Nephite people included many of the indigenous peoples of the land who had joined with the Nephites, and needed to be taught about Jehovah.
Isaiah labored in vain because Israel would not listen. In Nephi’s case, it was Laman and Lemuel who would not listen.
Isaiah speaks specifically of Jacob and Israel, making a direct reference to the southern and northern kingdoms of Israel. In Isaiah, the prophet could bring Jacob again to Jehovah, but Israel would remain scattered. The message is that the prophet is to bring to repentance and reconciliation those whom he can.
Nephi saw his people as among those who were scattered and not yet gathered. He probably saw his mission as parallel to Isaiah’s, but where Isaiah preached to Jacob, or the southern kingdom, Nephi preached to those who were scattered and not yet gathered. Isaiah was for the Old World and Nephi for the New, but both were to bring the house of Israel to know their God.