1 Samuel 26:5-9

David then set out and came to the place where Saul had camped. And David saw the place where Saul lay, and Abner the son of Ner, the commander of his army; and Saul was lying in the circle of the camp, and the people were camped around him.

Then David said to Ahimelech the Hittite and to Abishai the son of Zeruiah, Joab’s brother, saying, “Who will go down with me to Saul in the camp?” And Abishai said, “I will go down with you.”

So David and Abishai came to the people by night, and behold, Saul lay sleeping inside the circle of the camp with his spear stuck in the ground at his head; and Abner and the people were lying around him.

Then Abishai said to David, “Today God has handed your enemy over to you; now then, please let me pin him with the spear to the ground with one thrust, and I will not do it to him a second time.”

But David said to Abishai, “Do not kill him, for who can reach out with his hand against the Lord’s anointed and remain innocent?”