Exodus 3:1

Now Moses kept the flock of Jethro his father in law, the
priest of Midian
Who was either the same with Reuel or Raguel, spoken of in the preceding chapter; or, as others think, a son of his, the father being now dead; seeing it was now forty years since Moses came into Midian, ( Acts 7:30 ) . Demetrius ^F3, an Heathen writer, expressly says that Jothor a son of Raguel, and Zipporah or Sepphora, as he calls her, was his daughter, whom Moses married: now this was the business Moses was chiefly concerned in during his stay in Midian; keeping the sheep of his father-in-law, in which great personages have have employed, and who have afterwards been called to the kingly office, as David; and this was an emblem of his feeding and ruling the people of Israel, and in it he was an eminent type of Christ, the great shepherd and bishop of souls: no doubt there were other things besides this in which Moses exercised himself in this course of time, and improved himself in the knowledge of things, natural, civil, and religious, and which the more qualified him for the important work he was designed for: it is thought that in this interval he wrote the book of Genesis, and also the book of Job:

and he led the flock to the backside of the desert;
of Sinai or Arabia, on the back part of which, it seems, were goodly pastures; and hither he led his flock to feed, which was about three days' journey from Egypt, ( Exodus 5:3 ) or rather into the desert ^F4, for Horeb or Sinai was not behind the desert, but in it:

and came to the mountain of God, even to Horeb;
so called either because of the appearance of God at this time, after related, or because of his giving the law and making the covenant with the people of Israel there; and it should be observed that that transaction was past when Moses wrote this book. Hither he led the sheep, they delighting in mountains, hence sometimes mountainous places are called (oiopola) , ^F5, because sheep delight to feed upon them ^F6.