The commentary of Zacharias Ursinus on the Heidelberg catechism pp. 617,18 objection 8
Obj. 8. The law is the letter which killeth, and is the ministration of death and condemnation. (2 Cor. 3 : 6, 7.) But there is no condemnation to Christians. Therefore, the law does not have respect to Christians who are in Christ Jesus.
Ans. There is here a fallacy of accident ; for the law is not in itself the letter which killeth ; since this comes to pass by the fault of men, who, the more clearly they perceive the difference between themselves and the law, the more fully do they give themselves over to despair in reference to their salvation, and are therefore slam by the law. Again, the law alone, without the gospel, is the letter, that is, it is the doctrine which merely teaches, demands obedience, denounces the wrath of God and death to such as are disobedient, without producing the spiritual obedience which it requires. But when it is joined with the gospel, which is the Spirit, it also commences to become the Spirit, which is effectual in the godly, inasmuch as those who are regenerated commence willingly and cheerfully to yield obedience to the law. The law, therefore, is the letter, 1. By itself and without the gospel. 2. In respect to those who are unregenerated. On the other hand, the gospel is the Spirit; that is, it is the ministration and means through which the Holy Ghost, which works spiritual obedience in us, is given; not indeed as though all who hear, would receive the Holy Ghost and be regenerated, but because faith, by which our hearts are quickened, so that they begin to yield obedience to the law, is received by it. It does not follow, therefore, that the law is no longer to be taught in the church; for Christ himself says: “I am not come to destroy the law, but to fulfill it.” (Matt. 5: 17.) And Paul also says, that we establish the law through faith. (Rom. 3: 31.) Christ fulfilled the law in two respects: his obedience and suffering. He was just and holy in himself and did not violate the law in a single instance, but partly performed in our behalf those things which he was not bound to do, and partly sustained the punishment of the law. He also fulfills the law in us in two ways, by teaching it and granting unto us his Spirit, that so we may commence obedience to it, as we proved when speaking of the abrogation of the law.
This truly reminds me of Romans Chapter 8
Rom 8:1 There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit.
Rom 8:2 For the law of the Spirit of life in Christ Jesus hath made me free from the law of sin and death.
Rom 8:3 For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh:
Rom 8:4 That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit.
Rom 8:5 For they that are after the flesh do mind the things of the flesh; but they that are after the Spirit the things of the Spirit.
Rom 8:6 For to be carnally minded is death; but to be spiritually minded is life and peace.
Rom 8:7 Because the carnal mind is enmity against God: for it is not subject to the law of God, neither indeed can be.
Rom 8:8 So then they that are in the flesh cannot please God.
Rom 8:9 But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his.
Rom 8:10 And if Christ be in you, the body is dead because of sin; but the Spirit is life because of righteousness.
Rom 8:11 But if the Spirit of him that raised up Jesus from the dead dwell in you, he that raised up Christ from the dead shall also quicken your mortal bodies by his Spirit that dwelleth in you.
Rom 8:12 Therefore, brethren, we are debtors, not to the flesh, to live after the flesh.
Rom 8:13 For if ye live after the flesh, ye shall die: but if ye through the Spirit do mortify the deeds of the body, ye shall live.
Rom 8:14 For as many as are led by the Spirit of God, they are the sons of God.
Rom 8:15 For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father.
Rom 8:16 The Spirit itself beareth witness with our spirit, that we are the children of God:
Rom 8:17 And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.