'Plunder' in the Bible

Then Saul said, “Let us go down after the Philistines by night and plunder them until the morning light, and let us not leave a man of them [alive].” They said, “Do whatever seems good to you.” Then the priest said, “Let us approach God here.”

Why did you not obey the voice of the Lord, but [instead] swooped down on the plunder [with shouts of victory] and did evil in the sight of the Lord?”