פּירוש אויף דברים 3:12

ואת הארץ הזאת AND THIS LAND mentioned above (v. 8), "from the brook of Arnon to Mount Hermon", ירשנו בעת ההוא WE POSSESSED AT THAT TIME.

ואת הארץ הזאת ירשנו, “and this land we have inherited;” this phrase is abbreviated; the line should have begun with the words: ‘”and this land which we have inherited at that time ...as well as its towns, I have given to the tribe of Reuven.” All of this has been explained in Numbers 32,33.

ואת הארץ הזאת ירשנו בעת ההיא, “and we inherited this land at that time.” Rashi says that the words ואת הארץ הזאת refer to the land mentioned just previously. The words מערורר אשר על נחל ארנון, are not connected to what has been described previously, but introduce a new section, seeing that the people of Israel inherited more territory, lands inherited by the tribes of Reuven and Gad mentioned at the end of the verse. This is clear from the fact that Mount Hermon is situated far to the north of the river Arnon. Nachmanides writes that in his view the words הארץ הזאת אשר ירשנו בעת ההיא וגגו' were all regions given to the tribe of Reuven.

מערער אשר על נחל ארנן FROM AROER, WHICH IS BY THE BROOK ARNON — this must not be connected with the first part of this verse (defining הארץ הזאת) but with its conclusion — with נתתי לראבני ולגדי I GAVE TO THE REUBENITES AND TO THE GADITES; however, as respects possession (taking by conquest) that was "[from the brook of Arnon] to Mount Hermon" (v. 8).