All the kings of the earth shall praise thee ... - That is, kings, princes, and rulers shall learn the words of promise; shall be made acquainted with the words which thou hast graciously spoken, and with their fulfillment, and shall be led to praise thee. This refers to a time, of which frequent prophetic mention is made in the Scriptures, when kings and rulers shall be converted to the true religion, and when they shall act an important part, by their example and influence, in maintaining and diffusing it. Compare Psalms 68:31-32; Isaiah 49:23.
Related Commentaries of Psalms 138:4
Psalms 138:4
4 All the kings of the earth shall praise thee, O LORD, when they hear the words of thy mouth.