Psalms 40:8 - Joseph Benson’s Commentary on the Old and New Testaments

I delight to do thy will This also, though in a general sense it may be true of David, and of all God's people, yet, if it be compared with the foregoing verse, and with the explication thereof in the New Testament, (in which those mysteries, which were darkly and doubtfully expressed in the Old Testament, are fully and clearly revealed,) it must be appropriated to Christ, of whom it is eminently true; and it is here observed as an act of heroic obedience, that he not only resolved to do, but delighted in doing the will of God, or what God had commanded him, which was to die, and that a most shameful, and painful, and cursed death. Yea, thy law is within my heart I do not only understand it, but receive it with heartiest love, delighting both to meditate on it, and to yield obedience to it.