1 Samuel 26:7-9

7 So David and Abishai came to the people by night, and, behold, Saul lay sleeping within the trench and his spear stuck in the ground at his head, but Abner and the people lay round about him.

8 Then Abishai said to David, God has delivered thy enemy into thy hand today; now, therefore, let me smite him, I pray thee, with the spear [and pin him] to the earth at once, and I will not [need] a second opportunity.

9 And David said to Abishai, Do not destroy him, for who has stretched forth his hand against the LORD'S anointed, and remained innocent?