Psalms 138:4

4.Let all kings of the earth praise thee Here he declares that the goodness he had experienced would be extensively known, and the report of it spread over all the world. In saying that even kings had heard the words of God’s mouth, he does not mean to aver that they had been taught in the true religion so as to be prepared for becoming members of the Church, but only that it would be well known everywhere that the reason of his having been preserved in such a wonderful manner was God’s having anointed him king by his commandment. (194) Thus although the neighboring kings reaped no advantage by that divine oracle, the goodness of God was illustrated by its being universally known, by his being called to the throne in an extraordinary manner. Having uniformly during the whole period of Saul’s severe and bloody persecution declared that he raised his standard in God’s name, there could be no doubt that he came to the crown by divine will and commandment. And this was a proof of divine goodness which might draw forth an acknowledgment even from heathen kings.