I Samuel 24:10, 18

Look, this day your eyes have seen that the LORD delivered you today into my hand in the cave, and someone urged me to kill you. But my eye spared you, and I said, ‘I will not stretch out my hand against my lord, for he is the LORD’s anointed.’

And you have shown this day how you have dealt well with me; for when the LORD delivered me into your hand, you did not kill me.