Matthew Henry on Psalms 103:15-18

How short is man's life, and uncertain! The flower of the garden is commonly more choice, and will last the longer, for being sheltered by the garden-wall, and the gardener's care; but the flower of the field, to which life is here compared, is not only withering in itself, but exposed to the cold blasts, and liable to be cropt and trod on by the beasts of the field. Such is man. God considers this, and pities him; let him consider it himself. God's mercy is better than life, for it will outlive it. His righteousness, the truth of his promise, shall be unto children's children, who tread in the footsteps of their forefathers' piety. Then shall mercy be preserved to them.