William Burkitt on Romans 3:31

Observe here, The wise and holy caution which our apostle uses to take away the calumny and reproach cast upon him, by the adversaries of the doctrine of free justification by faith; as if this would render the law of God void and altogether useless: Do we then make void the law of God? As if he had said, "There may be those that will say so, but untruly; for we establish the law; because we acknowledge, that without exact obedience and conformity to the law, both in our natures and in our lives, as a rule of living, there can be no salvation."

Learn hence, That the doctrine of justification by faith alone, doth not overthrow but establish the law.

Here note, That it is the moral, not ceremonial law, which the apostle speaks of. The ceremonial law is utterly abolished by the gospel; but the moral law is not abolished, but established by the gospel; or, if abolished, it is only as a covenant, not as a rule. Christ has relaxed the law in point of danger, but not in point of duty; for the law is holy, and just, and good, and is not disannulled, but established by the gospel: Because by the gospel we obtain grace, in some measure, to fulfill the law, and yield a sincere obedience to it; which, for the sake of Christ's perfect and spotless obedience, shall find a gracious acceptance with God.

Therefore, with the highest elevation of soul, let us bless God for Jesus Christ, and for the gospel revelation, which has so fully discovered, and clearly revealed to us the only way of justification by faith in the Son of God, who hath loved us, and washed us from our sins in his own blood. To whom be glory and dominion forever and ever Amen.