The days were not expired That is, the time allowed by Saul to David for the execution of this exploit. Two hundred He doubled the number required; to oblige Saul the more to the performance of his promise, and to show his great respect and affection to Saul's daughter.
Related Commentaries of 1 Samuel 18:26
1 Samuel 18:26-27
26 And when his servants told David these words, it pleased David well to be the king's son in law: and the days were not expired.e
27 Wherefore David arose and went, he and his men, and slew of the Philistines two hundred men; and David brought their foreskins, and they gave them in full tale to the king, that he might be the king's son in law. And Saul gave him Michal his daughter to wife.