Exodus 18:27

And Moses let his father in law depart; and he went his way into his own land.

Moses let his father-in-law depart ... into his own land. This statement confirms the view formerly taken of Rephidim, that it was not in Feiran, otherwise there was no occasion for Jethro to depart, for his way into Midian, and that of Moses to Sinai, lay in the same direction.

Lepsius, who maintains that Rephidim was in Wady Feiran, is obliged, in support of this theory, to resort to the hypothesis that the two first verses in this chapter did not originally form part of the sacred composition, Exo. 19:27 of Exodus 16:1 being followed by Exodus 19:3 of this chapter. In my opinion, the narrative ran thus: 'And Moses let his father-in-law depart; and he went his way into his own land. And Moses went up unto God,' etc. But there is no ground whatever for concluding that there was any interpolation.