"How great things," he says, "He has commanded our fathers, to make the same known to their sons?" [Psalm 78:5]. "That another generation may know, sons who shall be born and shall rise up, and they may tell to their sons" [Psalm 78:6]. "That they may put their hope in God, and may not forget the works of God, and may seek out His commandments" [Psalm 78:7]. "That they may not become, like their fathers, a crooked and embittering generation: a generation that has not guided their heart, and the spirit thereof has not been trusted with God" [Psalm 78:8]. These words do point out two peoples as it were, the one belonging to the Old Testament, the other to the New: for in that he says, he has implied that they received the commandments, "to make them known to their sons," but that they did not know or do them: but they received them themselves, to the end "that another generation might know," what the former knew not. "Sons who shall be born and shall arise." For they that have been born have not arisen: because they had not their heart above, but rather on the earth. For the arising is with Christ: whence has been said, "If you have arisen with Christ, savour ye the things which are above." [Colossians 3:1] "And they may tell them," he says, "to their sons, in order that they may put their hope in God."..."And may not forget the works of God:" that is to say, in magnifying and vaunting their own works, as though they did them themselves; while "God it is that works," in them that work good things, "both to will and to work according to good will." [Philippians 2:13] "And may search out His commandments."...The commandments which He has commanded. How then should they still search out, whereas they have already learned them, save that by putting their hope in God, they do then search out His commandments, in order that by them, with His aid, they may be fulfilled? And he says why, by immediately subjoining, "and its spirit has not been trusted with God," that is, because it had no faith, which does obtain what the Law does enjoin. For when the spirit of man does work together with the Spirit of God working, then there is fulfilled that which God has commanded: and this does not come to pass, except by believing in Him that does justify an ungodly man. [Romans 4:5] Which faith the generation crooked and embittering had not: and therefore concerning the same has been said, "The spirit thereof has not been trusted with God." For this has been said much more exactly to point out the grace of God, which does work not only remission of sins, but also does make the spirit of man to work together therewith in the work of good deeds, as though he were saying, his spirit has not believed in God. For to have the spirit trusted with God, is, not to believe that his spirit is able to do righteousness without God, but with God. For this is to believe in God: which is surely more than to believe God. For ofttimes we must believe even a man, though in him we must not believe. To believe in God therefore is this, in believing to cleave unto God who works good works, in order to work with Him well....
[AD 430] Augustine of Hippo on Psalms 78:5-8