David is a good man.
Here we see David running for his life. You see him behaving well, just trying to survive. You see him risking his life to save a city even while he’s on the run. You see Saul punish priests and there families for helping a man they did not even know they should not help. You get a nice little anecdote of how crafty David can be, pretending to be mad in order to make himself seem nonthreatening.
Mostly, though, you see David get his chance to kill Saul and secure his own safety. The crown, too, but mostly his safety. You see David get that chance and refuse to take it, because Saul, too, had been anointed by God. Saul was king because God chose him. Yes, God chose David to replace Saul, but that didn’t mean David had any right to speed up the timeline.
I think he loved Saul. He was taken into Saul’s house when he was still young. He played music to sooth Saul when he was in a temper. I can imagine how emotional those moments would have been, how vulnerable Saul would have been. It’s easy to imagine that Saul would have confided in David as he was calming down. And even if he didn’t, David loved two of Saul’s children. How could he kill his wife’s father? His best friend’s father? Even if they understood, how could he ever look at them again?
This isn’t just some cold and distant king trying to kill the prophesied replacement. This was his father-in-law. This was a man he served. This was a man he lived with. This was a man he knew. A man whose weaknesses he knew. A man whose joys and sorrows he knew. A man he loved that had been hunting him. That had driven him from his home, his wife, his friend. That had assumed the worst about him at every turn when all he had ever been was loyal.
How complicated his emotional state must have been. Can you imagine?
So he couldn’t do it. He couldn’t kill Saul no matter what Saul had done. He’s a good man. But let’s remember, even in his heroics, he’s still just a man.