John Gill Commentary 2 Samuel 5:18

"Now the Philistines had come and spread themselves in the valley of Rephaim." — 2 Samuel 5:18 (ASV)

The Philistines also came and spread themselves in the valley of Rephaim. Or "of the giants", as (Joshua 15:8); which lay to the west of Jerusalem; of which, (See Gill on Joshua 15:8); the Philistines spreading themselves in it, shows that they were very numerous.