1SA 18:27

27 David and his men went and killed, [not 100, but] 200 Philistines! He brought their foreskins to Saul, and counted them [while Saul was watching], in order to prove that he had [done what the king required so that he could become Saul’s son-in-law. So then Saul was obligated] to allow David to marry his daughter Michal.