Exodus 18:24-27

So Moses listened to his father-in-law and did everything that he had said. Moses chose able men from all Israel and made them heads over the people, leaders of thousands, of hundreds, of fifties and of tens [from the highest to the lowest judicial levels]. And they judged the people at all times; they would bring the difficult cases to Moses, but every minor dispute they judged and decided themselves. Then Moses said goodbye to his father-in-law, and Jethro went back to his own land (Midian).