1 Samuel 26:8-12

Then Abishai said to David, “God has given your enemy into your hand this day; now then, please let me strike him with the spear driving it to the ground with one stroke, and I will not strike him the second time.” But David said to Abishai, “Do not kill him, for who can put out his hand against the LORD’S anointed [king] and be guiltless (innocent)?” David also said, “As the LORD lives, most certainly the LORD will strike him [in His own time and way], or his day will come and he will die, or he will go down into battle and be carried off [dead]. The LORD forbid that I would put out my hand against the LORD’S anointed; but now take the spear that is by his head and the jug of water, and let us go.” So David took the spear and the jug of water from beside Saul’s head, and they left, and no one saw or knew nor did anyone awaken, because they were all sound asleep, for a deep sleep from the LORD had fallen on them.