Albert Barnes Commentary 1 Samuel 22:7

"And Saul said unto his servants that stood about him, Hear now, ye Benjamites; will the son of Jesse give every one of you fields and vineyards, will he make you all captains of thousands and captains of hundreds," — 1 Samuel 22:7 (ASV)

You Benjamites - This shows how isolated the tribes still were, and how for the most part, Saul was surrounded only by his own tribesmen.