1 Samuel 24:10, 18

Behold, this day thine eyes have seen how that the LORD had delivered thee to day into mine hand in the cave: and some bade me kill thee: but mine eye spared thee; and I said, I will not put forth mine hand against my lord; for he is the LORD's anointed.

And thou hast shewed this day how that thou hast dealt well with me: forasmuch as when the LORD had delivered me into thine hand, thou killedst me not.