Behold, thou shalt call a nation that thou knowest not, and nations that knew not thee shall run unto thee because of the LORD thy God, and for the Holy One of Israel; for he hath glorified thee.
Behold, thou - Yahweh addresses Messiah.
Shalt call a nation (that) thou knowest not, and nations (that) knew not thee shall run unto thee. God must call, before man can, or will, run (Song of Solomon 1:4; John 6:44). Not merely shall come, but run eagerly.
That thou knowest not - now as thy people (so in Matthew 7:23).
Nation ... nations - gradation; from Israel, one nation, the Gospel spread to many nations, and will do so more fully on Israel's conversion.
That knew not thee - (Isaiah 52:15; Ephesians 2:11-12.)
Because of the Lord thy God ... for He hath glorified thee - (Isaiah 60:5; Isaiah 60:9; Zechariah 8:23), where similar language is directed to Israel, because of the identification of Israel with Messiah, who is the ideal Israel; Matthew 2:15: cf. with Hosea 11:1: see Acts 3:13.)