Ps 138:4

138:4 All the kings of the earth. David knows that his individual praise is unworthy of the greatness of God. He envisions all the rulers of the world calling upon the Lord. This never happened during the period of the Old Testament; if anything, the kings of the earth were opposed to God (Ps. 2; 48). After the coming of Christ, the gospel was extended to the nations (note on 133:title). In the end, all the kings of the earth will bring their glory into the New Jerusalem (Rev. 21:24).