Charles H. Spurgeon on Psalms 117:2

For his merciful kindness is great toward us. By which is meant not only his great love toward the Jewish people, but towards the whole family of man. The Lord is kind to us as his creatures, and merciful to us as sinners, hence his merciful kindness to us as sinful creatures. This mercy has been very great, or powerful. The mighty grace of God has prevailed even as the waters of the flood prevailed over the earth: breaking over all bounds, it has flowed towards all portions of the multiplied race of man. In Christ Jesus, God has shown mercy mixed with kindness, and that to the very highest degree. We can all join in this grateful acknowledgment, and in the praise which is therefore due. And the truth of the Lord endureth for ever. He has kept his covenant promise that in the seed of Abraham should all nations of the earth be blessed, and he will eternally keep every single promise of that covenant to all those who put their trust in him. This should be a cause of constant and grateful praise, wherefore the Psalm concludes as it began, with another Hallelujah, Praise ye the LORD.