If we read down just a little further; Paul starts to pull this thought together.
21 Consequently, I am finding the law that, at my willing to be doing the ideal, the evil is lying beside me." 22 For I am gratified with the law of God as to the man within,
23 yet I am observing a different law in my members, warring with the law of my mind, and leading me into captivity to the law of sin which is in my members."
we know that the law is spiritual; but I am unspiritual,
sold as a slave to sin. 15 I do not understand what I do.
For what I want to do I do not do, but what I hate I do. 16 And if I do what I do not want to do, I agree that the law is good. 17 As it is, it is no longer I myself who do it, but it is sin living in me. 18 For I know that good itself does not dwell in me, that is, in my sinful nature.[
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For I have the desire to do what is good, but I cannot carry it out. 19
For I do not do the good I want to do, but the evil I do not want to do—this I keep on doing. 20 Now if I do what I do not want to do, it is no longer I who do it, but it is sin living in me that does it.
21
So I find this law at work: Although I want to do good, evil is right there with me. 22 For in my inner being I delight in God’s law; 23
but I see another law at work in me, waging war against the law of my mind and making me a prisoner of the law of sin at work within me.''
As you mentioned the above, what law is being transgressed? In what regard is sin being committed?
Is Saul committing murder, adultery, stealing, carving out idols, failing to honour his parents, bearing false witness? Are these the things he cannot stop doing?
Are these the things he is a slave to doing?
Are these the things he hates but continues doing anyway?
Are these the evils that are there with him, that he is a slave to doing?
No! its all about what goes on, on the inside of him, thoughts/desires, coveting! You cannot control your thoughts as easily as you can obey outwardly
A fuller explanation of what he wrote in verses7-11, which is the reason he wrote 4-6