There are two reasons why David was able to get so close to Saul. The first has to do with the preparations of Saul’s army. Abner, knowing that David had previously spared Saul’s life when he was given a golden opportunity to kill him (1 Samuel 24:1–22), did not expect David to attack or harm Saul. As a result he probably set up only a few watches in the night, confident that there was nothing to fear from David and his men.1 In addition to a lack of wariness on the part of Saul’s army, David and Abishai were able to get close to Saul because the Lord placed a deep sleep on them.2
7 So David and Abishai went to the army by night. And there lay Saul sleeping within the encampment, with his spear stuck in the ground at his head, and Abner and the army lay around him.