1 Samuel 18:27-30

David arose and went, he and his men, and killed two hundred Philistine men, and David brought their foreskins [as proof of death] and presented every one of them to the king, so that he might become the king’s son-in-law. So Saul gave him Michal, his [younger] daughter, as a wife. When Saul saw and knew that the LORD was with David, and that Michal, his daughter, loved him, Saul was even more afraid of David; and Saul became David’s constant enemy. Then the Philistine commanders (princes) came out to battle, and it happened as often as they did, that David acted more wisely and had more success than all Saul’s servants. So his name was highly esteemed.