1 Samuel 24:16-22

16When David had finished saying these things, Saul called back, “Is that your voice, David my son?”

Then Saul wept aloud 17and said to David, “You are more righteous than I, for you have rewarded me with good, though I have rewarded you with evil. 18And you have declared this day how you have treated me well, for when the LORD delivered me into your hand, you did not kill me. 19When a man finds his enemy, does he let him go away unharmed? May the LORD reward you with good for what you have done for me this day.

20Now I know for sure that you will be king and that the kingdom of Israel will be established in your hands. 21So now, swear to me by the LORD that you will not cut off my descendants or wipe out my name from my father’s house.”

22So David gave his oath to Saul. Then Saul returned home, but David and his men went up to the stronghold.