The words, “said I,” are not in the Hebrew. The words “rise up, and get you over the brook Zered” (Numbers 21:12 note) connect themselves with Deuteronomy 2:9, and form the conclusion of what God said to Moses.
Related Commentaries of Deuteronomy 2:13
Deuteronomy 2:13
13 Now rise up, said I, and get you over the brookd Zered. And we went over the brook Zered.