At the mount of God— See note on ch. Exodus 3:1. The Israelites were not yet come to this mount of God; but Moses, says Houbigant, being about to relate the departure from Rephidim to the desart of Sinai, where was Horeb, the mountain of GOD, first finishes what was to be related concerning Jethro, and annexes the departure to the mountain of God, mentioned in Exodus 18:1 of the following chapter, to those miracles which were wrought in that mountain, as to the principal event; and not to the visit of Jethro, which was a kind of episode, and which was not of so great moment as to interrupt the future narration. There is no impropriety therefore in Moses's neglecting the order of time, where the cause appears why he relates those things first which happened afterwards. It is, however, supposed by many, that this event is recorded in its due place.
Related Commentaries of Exodus 18:5
Exodus 18:5
5 And Jethro, Moses' father in law, came with his sons and his wife unto Moses into the wilderness, where he encamped at the mount of God: