Jesus will quote the full content of this prophecy in 3 Nephi 20:16-17 and in even greater detail in 3 Nephi 21:12-15. Even though Jesus has not identified the prophet he is quoting, it actually taken from the writings of Micah in the Old Testament in Micah 5:7-15.
In any event, Jesus wanted the Gentiles to know that this western hemisphere had been promised to the seed of Joseph as their inheritance, and the Gentiles would receive a legacy in this land only as they joined with the house of Israel and sustained the seed of Joseph.