Exodus 18:25

“And Moses chose able men out of all Israel, etc.] He looked among them, and selected the best of them, such as most answered to the qualifications it was requisite they should have; and though only one of them is here mentioned, which is the first Jethro gave, yet no doubt they were all attended to, though not expressed: and made them heads over the people; rulers, governors, judges, and officers; this is a general word, comprehending their several particular offices they sustained; which seem to be chiefly distinguished by the different numbers of people, or families, under them, otherwise their work and office were much the same: rulers of thousands, rulers of hundreds, rulers of fifties,…”

“Exo 18:21; Deu 1:15; Act 6:5 Exodus 18:26”

“The judges chosen were arranged as chiefs (שׂרים) over thousands, hundreds, fifties, and tens, after the analogy of the military organization of the people on their march ( Num 31:14), in such a manner, however, that this arrangement was linked on to the natural division of the people into tribes, families, etc. (see my Archologie, 140). For it is evident that the decimal division was not made in an arbitrary manner according to the number of heads, from the fact that, on the one hand, the judges were chosen from the heads of their tribes and according to their tribes ( Deu 1:13); and on the other hand, the larger divisions of the tribes, viz., the families (mishpachoth), were also called…”