I Samuel 26:8-12

Then Abishai said to David, “God has delivered your enemy into your hand this day. Now therefore, please, let me strike him at once with the spear, right to the earth; and I will not have to strike him a second time!” But David said to Abishai, “Do not destroy him; for who can stretch out his hand against the LORD’s anointed, and be guiltless?” David said furthermore, “As the LORD lives, the LORD shall strike him, or his day shall come to die, or he shall go out to battle and perish. The LORD forbid that I should stretch out my hand against the LORD’s anointed. But please, take now the spear and the jug of water that are by his head, and let us go.” So David took the spear and the jug of water by Saul’s head, and they got away; and no man saw or knew it or awoke. For they were all asleep, because a deep sleep from the LORD had fallen on them.