1 Samuel 18:25-27

Then Saul said, “This is what you shall say to David: ‘The king wants no dowry except a hundred foreskins of the Philistines, to take vengeance on the king’s enemies.’ ” Now Saul’s intention was to cause David’s death at the hand of the Philistines. When his servants told David these words, it pleased him to become the king’s son-in-law. Before the time [for the marriage] arrived, 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.