1 Samuel 26:5-15

5 Then David rose and came to the place where Saul had encamped; and David saw the place where Saul lay, with Abner the son of Ner, the commander of his army; Saul was lying within the encampment, while the army was encamped around him.
6 Then David said to Ahim'elech the Hittite, and to Jo'ab's brother Abi'shai the son of Zeru'iah, "Who will go down with me into the camp to Saul?" And Abi'shai said, "I will go down with you."
7 So David and Abi'shai 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.
8 Then said Abi'shai to David, "God has given your enemy into your hand this day; now therefore let me pin him to the earth with one stroke of the spear, and I will not strike him twice."
9 But David said to Abi'shai, "Do not destroy him; for who can put forth his hand against the LORD'S anointed, and be guiltless?"
10 And David said, "As the LORD lives, the LORD will smite him; or his day shall come to die; or he shall go down into battle and perish.
11 The LORD forbid that I should put forth my hand against the LORD'S anointed; but take now the spear that is at his head, and the jar of water, and let us go."
12 So David took the spear and the jar of water from Saul's head; and they went away. No man saw it, or knew it, nor did any awake; for they were all asleep, because a deep sleep from the LORD had fallen upon them.
13 Then David went over to the other side, and stood afar off on the top of the mountain, with a great space between them;
14 and David called to the army, and to Abner the son of Ner, saying, "Will you not answer, Abner?" Then Abner answered, "Who are you that calls to the king?"
15 And David said to Abner, "Are you not a man? Who is like you in Israel? Why then have you not kept watch over your lord the king? For one of the people came in to destroy the king your lord.