Destroy him that remaineth of the city - i. e., shall destroy those of every city that had previously escaped. The phrase tersely describes a conqueror who first defeats his enemies in battle, and then hunts out the fugitives until he has cut off all of every place (compare 1 Kings 11:16).
The victories of David were a partial accomplishment of the predictions Numbers 24:14, Numbers 24:18, but did not exhaust them.
It is apparent that Edom and Moab are named by Balaam, as they are also by the prophets (compare e. g., Isaiah 11:14), as representatives of the pagan nations Numbers 24:8 who were hostile to the theocracy. As Jacob therefore figures as a constant type of the kingdom of Messiah in the prophets, so do Edom and Joab of the enemies of that kingdom; and in the threatened ruin of Edom and Moab is indicated the eventual destruction of all that resist the kingdom of God in its power.
The “Star” and “Sceptre” of the prophecy, like the “Sceptre” and “Lawgiver” of Genesis 49:10, point also naturally to a line of princes rather than to an individual; or rather are emblems of the kingdom of Israel generally. Thus, the victories of David and his successors, generation after generation, over Edom and Moab, are unquestionably recurring and progressive accomplishments of what Balaam foretold; but in addition the prophecy reaches forward to some further and culminating accomplishment; and that too in “the latter days” Numbers 24:14, the ordinary prophetic designation for the time of the Messiah (compare the marginal references).
To a Christian the connection between the Star and Seeptre of Balaam and the Star of the king of the Jews, which the wise men saw Matthew 2:2, is self-evident.