Numbers 33:13

And they departed from Dophkah, and encamped in Alush. The strong fort, as the Targum of Jonathan calls it; this was twelve miles from Dophkah: according to the Jewish chronology F4 Seder Olam Rabba, c. 5. p. 17. , this Alush is the wilderness of Sin, where the Israelites came on the fifteenth day of the seventh month from their going out of Egypt; and they say, that in Alush the sabbath was given them, and that there they kept the first sabbath, as it is said:

and the people rested on the seventh day , Exodus 16:30 .