Either,
1. All neighbouring kings; or,
2. The generality of kings and princes upon earth. And so this is a prophecy of the calling of the Gentiles, which seems to be confirmed by the next verse, which expresseth their extraordinary joy; and an eminent advancement of God's glory, which agrees much better to this great occasion, than to that of David's exaltation to the throne, wherein the other kings of the earth were not much concerned. The words of thy mouth; either,
1. Thy promises declared unto them by me; or,
2. The gospel preached among them.