Adam Clarke on Judges 7:16

He divided the three hundred men - Though the victory was to be from the Lord, yet he knew that he ought to use prudential means; and those which he employed on this occasion were the best calculated to answer the end. If he had not used these means, it is not likely that God would have delivered the Midianites into his hands. Sometimes, even in working a miracle, God will have natural means used: Go, dip thyself seven times in Jordan. Go, wash in the pool Siloam.