O give thanks unto the Lord, for he is good - See the notes at Psalms 106:1.
For his mercy endureth for ever - He is unchanging in his mercy. It is an attribute of his very nature. He is constantly manifesting it. The word rendered “mercy” here, however - חסד chesed - is more general in its signification than our word “mercy.” Our word means “favor shown to the guilty;” the Hebrew word means kindness, goodness, benignity in general. It is this which is celebrated in the psalm before us.