John Wesley on Numbers 31:6

Them and Phinehas - Who had the charge not of the army, as general, (an office never committed to a priest in all the Old Testament) but of the holy instruments, and was sent to encourage, and quicken, them in their enterprize. The holy instruments - The holy breast - plate, wherein was the Urim and Thummim, which was easily carried, and very useful in war upon many emergent occasions.