Deuteronomy 1:1
1 This is what Moses said to all of Israel in the Transjordanian wilderness, the arid rift valley opposite Suph, between Paran and Tophel, Laban, Hazeroth, and Di Zahab. 2 Now it is ordinarily an eleven-day journey from Horeb to Kadesh Barnea by way of Mount Seir. 3 However, it was not until the first day of the eleventh month of the fortieth year that Moses addressed the Israelites just as the Lord had instructed him to do.
Deuteronomy 3:20
19 But your wives, children, and livestock (of which I know you have many) may remain in the cities I have given you. 20 You must fight until the Lord gives your countrymen victory as he did you and they take possession of the land that the Lord your God is giving them on the other side of the Jordan River. Then each of you may return to his own territory that I have given you.” 21 I also commanded Joshua at the same time, “You have seen everything the Lord your God did to these two kings; he will do the same to all the kingdoms where you are going.
Notes and References
"... The narrator pictures Moses speaking “across the Jordan” many times in Deuteronomy. This was one of the early signs that led people to question whether Moses himself was the author of the Torah. These words reflect the perspective of an author who is in Israel. The author thus refers to Moses’ location in Moab as “across the Jordan.” This would not be the perspective of an author who is in Moab at the time. See also Deuteronomy 3:20 ..."
Friedman, Richard Elliott The Bible with Sources Revealed: A New View Into the Five Books of Moses (p. 309) Harper San Francisco, 2005