Genesis 34:12

“If her father absolutely refuses to give her to him, he shall pay money equal to the dowry for virgins.

So Saul’s servants spoke these words in David’s hearing. But David said, “Is it trivial in your eyes to become the king’s son-in-law, since I am a poor man and lightly esteemed?”

Saul then said, “Thus you shall say to David, ‘The king does not desire any dowry except one 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.