1 Samuel 24:3-7

He came to the sheep pens along the way; a cave was there, and Saul went in to relieve himself. David and his men were far back in the cave. The men said, “This is the day the LORD spoke of when he said to you, ‘I will give your enemy into your hands for you to deal with as you wish.’ ” Then David crept up unnoticed and cut off a corner of Saul’s robe. Afterward, David was conscience-stricken for having cut off a corner of his robe. He said to his men, “The LORD forbid that I should do such a thing to my master, the LORD’s anointed, or lay my hand on him; for he is the anointed of the LORD.” With these words David sharply rebuked his men and did not allow them to attack Saul. And Saul left the cave and went his way.