Charles Ellicott Commentary Judges 20:10

"and we will take ten men of a hundred throughout all the tribes of Israel, and a hundred of a thousand, and a thousand out of ten thousand, to fetch victuals for the people, that they may do, when they come to Gibeah of Benjamin, according to all the folly that they have wrought in Israel." — Judges 20:10 (ASV)

Ten men of an hundred. —A tenth of the nation, probably chosen by lot, is to be responsible for the provisioning. They do not anticipate any other difficulty.