John Calvin Commentary Exodus 18:1

"Now Jethro, the priest of Midian, Moses` father-in-law, heard of all that God had done for Moses, and for Israel his people, how that Jehovah had brought Israel out of Egypt." — Exodus 18:1 (ASV)

When Jethro, the priest of Midian. This chapter consists of two parts. First of all, the arrival of Jethro in the camp is related, and his congratulation of Moses for the prosperity of his enterprise, together with the praise and sacrifice offered to God. Secondly, his proposed form of government for the people is set forth, as a result of which judges and rulers were chosen, lest Moses sink under his heavy task.

Most commentators think that Zipporah, having been enraged because of her son’s circumcision, had turned back during their journey and gone to live with her father; but this does not seem probable to me. For Moses would never have allowed his sons to be deprived of the redemption of which he was the minister, nor would it have been consistent for them to be appointed priests later if God had not been their Redeemer. Besides, if he had left his wife and children in safety and had advanced alone to the contest, he would have been rightly suspected of deceit or of excessive cowardice. Therefore, I have no doubt that he, together with his family, endured that miserable yoke of bondage by which they were long oppressed, and by this proof demonstrated his faithfulness, so that greater authority might accompany his calling.

The statement, then, in the second verse, after he had sent her back, I interpret as referring to Moses, because he had sent his wife back from the wilderness to visit her father, either having yielded to a desire natural to her as a woman, or, motivated by his own piety, he had wished to show respect in this way to an old man closely related to him. There is something forced and cold in the interpretation that some would supply: “after he had sent back gifts.” The text reads very well this way: After Moses had sent back his wife, she was brought back by his father-in-law, thus returning and repaying his kindness.