Saul replied, "Say to David, 'The king wants no other price1 for the bride than a hundred Philistine foreskins, to take revenge2 on his enemies.' " Saul's plan3 was to have David fall by the hands of the Philistines.
References for 1 Samuel 18:25
When the attendants told David these things, he was pleased to become the king's son-in-law. So before the allotted time elapsed,
David and his men went out and killed two hundred Philistines. He brought their foreskins and presented the full number to the king so that he might become the king's son-in-law. Then Saul gave him his daughter Michal4 in marriage.
References for 1 Samuel 18:27