Deuteronomy 1:18

And I commanded you at that time all the things which ye should do. — “At that time,” i.e., after your departure from Horeb. This is as much as to say that the exhortations given in Deuteronomy had already been given on the way from Sinai to Kadesh-barnea. (Comp. what has been said above on the two first verses of this chapter.) This verse goes far to justify the view taken there.