1 Samuel 24:17-21

And he said to David, “You are more righteous than I; for you have dealt well with me, while I have dealt maliciously with you.

You have declared today that you have done good to me, that the Lord handed me over to you and yet you did not kill me.

Though if a man finds his enemy, will he let him go away unharmed? May the Lord therefore reward you with good in return for what you have done to me this day.

Now, behold, I know that you will certainly be king, and that the kingdom of Israel will be established in your hand.

So now swear to me by the Lord that you will not cut off my descendants after me, and that you will not eliminate my name from my father’s household.”