Kommentar zu Dewarim 2:20

ארץ רפאים תחשב IT (AMMON) ALSO WAS ACCOUNTED A LAND OF REPHAIM. — It also is accounted a land of Rephaim because the Rephaim formerly dwelt in it, but yet it is not that land which I gave to Abraham.

TEICHASHEIV’ (ACCOUNTED). The land of Ammon, too, is considered part of the land of Rephaim; in other words, it is included within it. Similarly, from the Shihor, which is before Egypt, even unto the border of Ekron northward ‘teichasheiv’ (is accounted) to the Canaanites.¹⁷⁴Joshua 13:3. So also, the sons of Rimmon the Beerothite, of the children of Benjamin; for Beeroth also ‘teichasheiv’ (is accounted) to Benjamin.¹⁷⁵II Samuel 4:2. It is possible that such is also the meaning of the expression written above [with reference to Moab], these also are ‘yeichashvu’ Rephaim,¹⁷⁶Above, Verse 11. Scripture stating that the Emim who formerly dwelled there¹⁷⁷See ibid., Verse 10. are also “accounted”¹⁷⁸In Verse 10 above Ramban explained yeichashvu as an expression of importance and esteem. Here Ramban explains it as “accounted” [to the Rephaim]. Rephaim since they were part of them, and they were as the Anakim,¹⁷⁶Above, Verse 11. and therefore they [the Moabites] called them ‘Emim’¹⁷⁶Above, Verse 11. [because their “dread,” like that of the Anakim (giants) lay upon the people]. This is the correct interpretation.
Thus the land of Rephaim was very large, and from it, Moab and Ammon took their lands. The balance remained for the Rephaim themselves, for Og, who dwelled in Ashtaroth, was of them, as is stated, and they smote the Rephaim in Ashteroth-karnaim.¹⁵⁵Ibid., Verse 5. And in the Book of Joshua it is written, and cut down a space for thyself there in the land of the Perizzites and of the Rephaim.¹⁷⁹Joshua 17:15. Therefore, Scripture says of the border of Moab and Ammon that it is “accounted to the Rephaim,” [still calling them “Rephaim,” the name by which they were originally known]. The Moabites and the Ammonites were the ones that changed [the name of the Rephaim] to other names: [the Moabites calling them] Emim and [the Ammonites calling them] Zamzummim.

ארץ רפאים תחשב אף היא, there can be no question that the Ammonites had no legal right to dispossess these people; the only reason why they succeeded in doing so was because it was G’d’s will.