Then David ran, and stood over the Philistine, and took his sword, and drew it out of the sheath of it, and killed him, and cut off his head therewith. When the Philistines saw that their champion was dead, they fled.
It was a trophy that David had, and he wasn't gonna let the thing go. He was gonna carry it around for a few days. Must have been a big head too, you know, the guy's nine foot, six inches tall.