But the mercy of the Lord - The favor of the Lord; or, his loving-kindness.
Is from everlasting to everlasting - Is from the eternity past to the eternity to come. It had its foundation in the eternal decrees of God; it has its security in his purpose that where it is conferred, it shall not be withdrawn. It had no beginning; it will have no end. There never was a period in the past when it was not the purpose of God to save his people; there never will be a period in the future when it will be said that his saving mercy has ceased. It would be difficult to think of a statement which would at the same time, in so few words, confirm at once the doctrine of the divine decrees, and the doctrine of the perseverance of the saints. If either of these doctrines is denied, then what is here stated by the psalmist is not true: if the doctrine of the divine decrees is denied, then his purpose of mercy had a beginning, and is not “from everlasting;” if the doctrine of the perseverance of the saints is denied, then his mercy has an end, and is not “to everlasting.”
Upon them that fear him - In respect to those who are his true worshippers, or his true people.
And his righteousness - His righteous purpose; or, his purpose in regard to their “becoming” righteous.
Unto children’s children - literally, “sons of sons.” That is, his purposes embrace the children and children’s children of the righteous; or, they are included in the covenant of mercy. See the notes at Acts 2:39. Compare Exodus 20:6.