Thou hast taught me, O God, from my youth: and till now I will declare thy wonderful works.

“"O God, You have taught me from my youth" [Psalm 71:17]. What have you taught me? That of Your righteousness alone I ought to be mindful. For reviewing my past life, I see what was owing to me, and what I have received instead of that which was owing to me. There was owing punishment, there has been paid grace: there was owing hell, there has been given life eternal. "O God, You have taught me from my youth." From the very beginning of my faith, wherewith You have renewed me, You taught me that nothing had preceded in me, whence I might say that there was owing to me what You have given. For who is turned to God save from iniquity? Who is redeemed save from captivity? But who can say that unjust was his captivity, when he forsook his Captain and fell off to the deserter? God is for our Captain, the devil a deserter: the Captain gave a commandment, the deserter suggested guile: where were your ears between precept and deceit? Was the devil better than God? Better he that revolted than He that made you? You believed what the devil promised, and found what God threatened. Now then out of captivity being delivered, still however in hope, not yet in substance, walking by faith, not yet by sight, "O God," he says, "You have taught me from my youth." From the time that I have been turned to You, renewed by You who had been made by You, re-created who had been created, re-formed who had been formed: from the time that I have been converted, I have learned that no merits of mine have preceded, but that Your grace has come to me gratis, in order that I might be mindful of Your righteousness alone.”

“O God, thou hast taught me from my youth,.... The corruption of human nature; the weakness and impotence of it, to everything that is spiritually good; and the need of continual strength and grace from Christ, to go to him for righteousness and strength, life and salvation, and to walk by faith on him; the doctrine of justification by the righteousness of Christ, and the insufficiency of his own; the will, ways, and worship of God; and all the duties of religion, prayer, praise, &c. and whoever were the instruments, or whatever were the means, of teaching David these things, he ascribes it to God. Whether his parents, or the priests and Levites, taught him the sacrifices and ordinances of the law, it was the Lord that blessed instructions to him; and that taught him by providences and precepts, and by his Holy Spirit. And a wonderful blessing it is to be taught of God, and not of men, things relating both to doctrine and practice; and it is an addition to it to be taught these things early, as David was from his youth; and therefore the Lord was so soon the object of his faith and trust, Psa 71:5; and, as Timothy, from a child, was acquainted with the holy Scriptures, and the things contained in them, which are able to make wise unto salvation, Isa 29:13; and hitherto have I declared thy wondrous works: not only of nature and providence, but of grace; the treasuring up of all grace, and the blessings of it in Christ; the work of redemption by him; the work of regeneration and conversion by his Spirit; and the perseverance of the saints by his grace and strength; which are all wonderful and amazing. And as the psalmist saw his interest in these things, and had an experience of them, he declared them to others for their encouragement, and to the glory of all the three Persons; see Psa 66:16.”