Numbers 12:1 - Coke's Commentary on the Holy Bible

And Miriam and Aaron spake against Moses— Miriam is mentioned before Aaron, probably because she was the beginner of this sedition, and drew Aaron into it. It is uncertain what occasioned them to quarrel with him about his wife Zipporah: they might possibly be jealous of his being ruled too much by her and her relations; for it was by her father's advice that he constituted the judges and officers, mentioned in Exodus 18:21-22 and, perhaps, they imagined that she and Hobab had a hand in choosing the seventy elders, mentioned in the foregoing chapter: the history being immediately connected with that, would lead one at least to think that they have some relation to each other. Thus the real motive of the quarrel was jealousy: the pretended one, that his wife was a foreigner, not belonging to the commonwealth of Israel. An Ethiopian, we render it after the LXX; the Hebrew is כשׁית cushit, a Cushite, or Arabian woman; for she was of the land of Midian, a part of Arabia Petraea. See Exodus 2:16; Exodus 2:25.