1 Samuel 26:2-12

2 So Saul arose and went down to the wilderness of Ziph, with three thousand chosen men of Israel, to seek David in the wilderness of Ziph.
3 And Saul encamped on the hill of Hachi'lah, which is beside the road on the east of Jeshi'mon. But David remained in the wilderness; and when he saw that Saul came after him into the wilderness,
4 David sent out spies, and learned of a certainty that Saul had come.
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.