Psalm 117:2

For his merciful kindness is great towards us
Not us Israelites only, of whom David was, but Gentiles also; or otherwise there would be no force in the reason why all people and nations should praise the Lord: but it respects the time when these should become one people, partaking of the same grace, blessings, promises, and privileges; in which the grace, mercy, and lovingkindness of God, greatly appeared; "it prevailed over us" ^F16, as it may be rendered: the word is used of the prevailing of the waters of the flood over the earth, ( Genesis 7:18 ) ; and so may denote the exuberance of the grace of God, of the abounding and superabounding of it. There is an abundance of it in the heart of God, in his covenant, and in his Son; and which is displayed in redemption by him; in the forgiveness of sin; and in the conversion of sinners, and their everlasting salvation: particularly there has been an inundation or deluge of it in the Gentile world, where it has flowed and overflowed; where sin abounded, grace has much more abounded; and therefore the Lord is to be praised. And another reason follows,

and the truth of the Lord [endureth] for ever;
the faithfulness of God to his promises, not only made to the Jewish fathers concerning the Messiah, and redemption by him; but to the Gentiles, and concerning the blessing of all nations in the promised seed: and the faithfulness and truth of God, with respect to any of his promises, never fails; nor will his word of truth, the Gospel; nor Jesus Christ, who is the truth, and the truth of God; the truth of types, promises, and prophecies; see ( Psalms 43:3 ) ; for he is the same today, yesterday, and for ever.

Praise ye the Lord;
for his superabounding grace, and eternal truth; even all the people of God, of all nations, Jews and Gentiles.