Commentaire sur Les Nombres 33:53

והורשתם את הארץ (lit., ye shall drive out the land) — this means: and you shall dispossess it of its inhabitants, and then, וישבתם בה YOU WILL DWELL IN IT — i.e., you will be able to remain in it, but if not, you will not be able to remain in it.

AND YE SHALL DRIVE OUT THE INHABITANTS OF THE LAND, AND DWELL THEREIN; FOR UNTO YOU HAVE I GIVEN THE LAND TO POSSESS IT. In my opinion this is a positive commandment,²⁴Among the great scholars who enumerate the individual 613 Commandments, Ramban was the first to mention this commandment [to conquer and settle in the Land of Israel etc.] as binding for all times. In his notes to Maimonides’ Sefer Hamitzvoth (Book of the Commandments), in the section on “additional” positive commandments, No. 4, Ramban discusses this opinion at length. Here in his commentary on the Torah, he mentions it briefly, relying presumably on his explanation in the work quoted above. in which He is commanding them to dwell in the Land and inherit it, because He has given it to them and they should not reject the inheritance of the Eternal.²⁵I Samuel 26:19. Thus if the thought occurs to them to go and conquer the land of Shinar or the land of Assyria or any other country and to settle therein, they are [thereby] transgressing the commandment of G-d. And that which our Rabbis have emphasized, the significance of the commandment of settling in the Land of Israel, and that it is forbidden to leave it [except for certain specified reasons], and [the fact] that they consider a woman who does not want to emigrate with her husband to live in the Land of Israel as a “rebellious [wife],”²⁶Kethuboth 110b: “If he wants to emigrate [to the Land of Israel] and she refuses, she may be forced to go there, and if she still refuses, she may be divorced without her kethubah (marriage contract — see Vol. II, pp. 385-386). and likewise the man²⁷“If she wants to emigrate [to the Land of Israel] and he refuses, he may be forced to go there, and if he still refuses, he must divorce her and give her the kethubah (ibid.). — the source of all these statements is here [in this verse] where we have been given this commandment, for this verse constitutes a positive commandment.²⁸“For all generations, every person being obliged in the performance thereof, even during the exile” (Ramban in his notes to Maimonides’ Sefer Hamitzvoth “additional” positive commandments, No. 4). This commandment He repeats in many places, such as Go in and possess the Land.²⁹Deuteronomy 1:8. “And when they refused to go up, it is written: but ye rebelled against the commandment of the Eternal your G-d (ibid., Verse 26 — Ramban on Sefer Hamitzvoth, ibid.). Rashi, however, explained: “And ye shall drive out the inhabitants of the Land — [if] you dispossess it of its inhabitants, then ye will be able to dwell therein, and to remain there, but if not, you will not be able to remain in it.” But our interpretation [of the verse] is the principal one.

והורשתם את הארץ, when you will wipe out the present inhabitants of that land your children will thereby acquire the right to treat it as their ancestral heritage. If you fail to drive out or wipe out the local population, the land will not become your heritage even though you have conquered it.