1 Samuel 18:17-18

17Saul said to David, “Here is my older daughter Merab. I will give her to you in marriage; only serve me bravely and fight the battles of the Lord.” For Saul said to himself, “I will not raise a hand against him. Let the Philistines do that!”

18But David said to Saul, “Who am I, and what is my family or my clan in Israel, that I should become the king’s son-in-law?”