Jamieson-Fausset-Brown on Numbers 31:8
the kings of Midian--so called, because each was possessed of absolute power within his own city or district; called also dukes or princes of Sihon (Jos 13:21), having been probably subject to that Amorite ruler, as it is not uncommon in the East to find a number of governors or pachas tributary to one great king.
Zur--father of Cozbi (Num 25:15).
Balaam also . . . they slew with the sword--This unprincipled man, on his dismissal from Balak, set out for his home in Mesopotamia (Num 24:25). But, either diverging from his way to tamper with the Midianites, he remained among them without proceeding farther, to incite them against Israel and to watch the effects of his wicked counsel; or, le…
Read the whole note in the consoleJohn Gill on Numbers 31:10
And they burnt all their cities wherein they dwelt, &c. ) So far as they went into the country, which, perhaps, might not be the whole land of Midian:
and all their goodly castles with fire; which were either the palaces of their princes and nobles, or such like great personages; or they were fortified places, for the security of their cities and country: the Targums of Onkelos and Jonathan interpret them of their houses of worship, their temples, and their altars.
John Calvin on Numbers 31:7-10
And they warred against the Midianites. It was a signal example of obedience, that 12,000 men did not refuse to engage in a war which was full of danger, when it was reasonable for them to object that it was not right for them to be exposed to butchery, as it were, whilst the people sat idly in the camp, who by their great numbers and with little trouble would have routed and overcome the enemy. It was therefore no common proof of piety, that they obeyed God's command, and sought for no pretext to cover their cowardice. God, too, shewed by the result that He did not rashly expose His servants to danger; for it is in His power to rescue those whom He takes under His protection, from a hundred…
Read the whole note in the consoleKeil & Delitzsch