'Foreskins' in the Bible

Saul then said, “Thus you shall say to David, ‘The king does not desire any dowry except a hundred foreskins of the Philistines, to take vengeance on the king’s enemies.’” Now Saul planned to make David fall by the hand of the Philistines.

David rose up and went, he and his men, and struck down two hundred men among the Philistines. Then David brought their foreskins, and they gave them in full number to the king, that he might become the king’s son-in-law. So Saul gave him Michal his daughter for a wife.