5 Then David's anger was greatly kindled against the man; and he said to Nathan, "As the Lord lives, the man who has done this deserves to die; 6 and he shall restore the lamb fourfold, because he did this thing, and because he had no pity." 7 Nathan said to David, "You are the man. Thus says the Lord, the God of Israel, 'I anointed you king over Israel, and I delivered you out of the hand of Saul; 8 and I gave you your master's house, and your master's wives into your bosom, and gave you the house of Israel and of Judah; and if this were too little, I would add to you as much more. 9 Why have you despised the word of the Lord, to do what is evil in his sight? You have smitten Uri'ah the Hittite with the sword, and have taken his wife to be your wife, and have slain him with the sword of the Ammonites.
Matthew Henry's Commentary on 2 Samuel 12:5-9
Commentary on 2 Samuel 12:1-14
(Read 2 Samuel 12:1-14)
God will not suffer his people to lie still in sin. By this parable Nathan drew from David a sentence against himself. Great need there is of prudence in giving reproofs. In his application, he was faithful. He says in plain terms, Thou art the man. God shows how much he hates sin, even in his own people; and wherever he finds it, he will not let it go unpunished. David says not a word to excuse himself or make light of his sin, but freely owns it. When David said, I have sinned, and Nathan perceived that he was a true penitent, he assured him his sin was forgiven. Thou shalt not die: that is, not die eternally, nor be for ever put away from God, as thou wouldest have been, if thou hadst not put away the sin. Though thou shalt all thy days be chastened of the Lord, yet thou shalt not be condemned with the world. There is this great evil in the sins of those who profess religion and relation to God, that they furnish the enemies of God and religion with matter for reproach and blasphemy. And it appears from David's case, that even where pardon is obtained, the Lord will visit the transgression of his people with the rod, and their iniquity with stripes. For one momentary gratification of a vile lust, David had to endure many days and years of extreme distress.