1 Samuel 26:7-11

So David and Abishai came to the people by night: and, behold, Saul lay sleeping within the place of the wagons, with his spear stuck in the ground at his head; and Abner and the people lay round about him. Then said Abishai to David, God hath delivered up thine enemy into thy hand this day: now therefore let me smite him, I pray thee, with the spear to the earth at one stroke, and I will not smite him the second time. And David said to Abishai, Destroy him not; for who can put forth his hand against Jehovah’s anointed, and be guiltless? And David said, As Jehovah liveth, Jehovah will smite him; or his day shall come to die; or he shall go down into battle and perish. Jehovah forbid that I should put forth my hand against Jehovah’s anointed: but now take, I pray thee, the spear that is at his head, and the cruse of water, and let us go.