1 Samuel 18:17-18

Then Saul said to David, “Behold I will give you my older daughter Merab as a wife; only be brave for me and fight the LORD’S battles.” For Saul thought, “My hand shall not be against him, but let the hand of the Philistines be against him.” David said to Saul, “Who am I, and what is my life or my father’s family in Israel, that I should be the king’s son-in-law?”