22 For I delight in the law of God after the inward man: (Romans 7:22 KJV)
William Burkitt’s Commentary
If by the inward man, we understand the mind and understanding of a man only, then the unregenerate person may be said to delight in the all of God, with Ezekiel’s hearers, Eze 33:32; with Herod, Mr 6:20; with the stony ground, Mt 13:20. That is, they delight and satisfy themselves with the bare hearing of the word, and with a notional and speculative knowledge of their duty; either the eloquence of the preacher whom they hear, or the pleasingness of some truths which they hear, affect them with a sudden joy: they delight to hear the word, but they take no delight to do it. It is neither a spiritual delight nor an abiding delight that such men take in the law of God.
If by the inward man, we understand that which St. Peter calls the hidden man of the heart, the new man, or the regenerate part in man, as being seated in the inward powers and faculties of the soul; then, to delight in the law of God is to love it for its purity and spirituality, because it makes holiness our duty; to take pleasure in the knowledge of the law, in meditating upon it, and in practising every good duty contained in it and enjoined by it.
Thus David did delight to do the will of God because the law of God was within his heart. Where there is lex in corde, there will be cor in lege; where the law of God is in the heart, there the heart will be engaged in that obedience which is by the law required, and by the Christians performed. He delights in the law, and the law is delighted by him.