His mercy - Favor shown to the miserable and the guilty.
Is on them - Is shown or manifested to them.
That fear him - That “reverence” or honor Him. One kind of fear is that which a servant has of a cruel master, or which a man has of a precipice, the plague, or death. This is not the “fear” which we ought to have toward God. It is the fear which a dutiful child has of a kind and virtuous father a fear of injuring his feelings; of dishonoring him by our life; of doing anything which he would disapprove. It is on those who have such fear of God that his mercy descends. This is the fear of the Lord which is the beginning of wisdom, Psalms 111:10; Job 28:28.From generation to generation - From one age to another - that is, it is unceasing; it continues and abounds. But it means also more than this. It means that God’s mercy will descend on the children and children’s children of those that fear him and keep his commandments, Exodus 20:6. In this respect it is an unspeakable privilege to be descended from pious parents; to have been the subject of their prayers, and to have received their blessing. It is also a matter of vast guilt not to copy their example and to walk in their steps. If God is “disposed” to show mercy to thousands of generations, how heavy will be the condemnation if the children of pious parents do not avail themselves of it and early seek his favor!