(The Book of Mormon and the King James texts are the same, therefore only one is quoted.)
Abraham was promised that in his seed (the literal seed, or the seed of the body) shall all the families of the earth be blessed, even with the blessings of the gospel” (Abraham 2:11). The gathering of the house of Jacob mentioned here by Isaiah will be in preparation for the fulfillment of the covenant made to Abraham.
Elder Orson Pratt says that this restoration of the house of Jacob will come through the Book of Mormon:
The house of Jacob has been made ashamed, and his face has waxed pale, ever since he was driven away from Lebanon or Canaan, but the Lord has now brought forth out of the ground a book which shall, accompanied by his power, restore the tribes of Jacob from the four quarters of the globe, and establish them in the land of Palestine and Lebanon forever; and His holy name they shall no more profane, but shall be a righteous people throughout all their generations, while the earth shall stand, and they shall possess their promised land again in eternity, never more to pass away; therefore, they shall never again be made ashamed. It is in vain for the Gentiles to seek the conversion of Jacob, and to bring about their great redemption, only in the way that the Lord God of Israel hath predicted and appointed: they may call meetings and conventions to convert the Jews, but let them know assuredly that the book spoken of by Isaiah is to accomplish the salvation of the house of Jacob, and bring about the restoration of all Israel, while the Gentiles who will not receive it and be numbered and identified with the house of Jacob, must surely perish, yea, and they shall be utterly wasted with storm and tempest, with earthquakes and famine, with the flame of devouring fire, and their fruitful lands shall be esteemed as a forest, while Jacob shall dwell in safety forever. [Works, 278; see also 2 Nephi 25:17–18; 29:1–2]