14 So in the morning David wrote a letter to Joab and sent it by the hand of Uriah. 15 He had written in the letter [h]the following: “[i]Station Uriah on the front line of the [j]fiercest battle and pull back from him, so that he may be struck and killed.” 16 So it was as Joab kept watch on the city, that he [k]stationed Uriah at the place where he knew there were valiant men. 17 And the men of the city went out and fought against Joab, and some of the people among David’s servants fell; and Uriah the Hittite also died. 18 Then Joab sent a messenger and reported to David all the events of the war. 19 He ordered the messenger, saying, “When you have finished telling all the events of the war to the king, 20 then it shall be that if the king’s wrath rises and he says to you, ‘Why did you move against the city to fight? Did you not know that they would shoot from the wall? 21 Who struck Abimelech the son of Jerubbesheth? Did a woman not throw an upper millstone on him from the wall so that he died at Thebez? Why did you move against the wall?’—then you shall say, ‘Your servant Uriah the Hittite also died.’”
22 So the messenger departed and came and reported to David everything that Joab had sent him to tell. 23 The messenger said to David, “The men prevailed against us and came out against us in the field, but we [l]pressed them as far as the entrance of the gate. 24 Also, the archers shot at your servants from the wall; so some of the king’s servants died, and your servant Uriah the Hittite also died.” 25 Then David said to the messenger, “This is what you shall say to Joab: ‘Do not let this thing [m]displease you, for the sword devours one as well as another; [n]fight with determination against the city and overthrow it’; and thereby encourage him.”
26 Now when Uriah’s wife heard that her husband Uriah was dead, she mourned for her husband. 27 When the time of mourning was over, David sent servants and [o]had her brought to his house and she became his wife; then she bore him a son. But the thing that David had done was evil in the sight of the Lord.
Not only was the thing that David did evil, but he used a foolish cover for it. Joab knew that only a fool would let his men get so close to the wall of the city when fighting, otherwise the archers would pick them off easily. There was a well known story where an old woman had killed a man with a millstone because he ventured too close to the wall.
But you can’t cover up your evil deeds forever, no matter how clever your cover story. God knows everything you do, and He will hold you accountable. Never doubt that God will deliver justice. Even more so, He will discipline those who know Him best and ought to know better.