Or HaChaim on Numbers 26:55/אור החיים על במדבר כ״ו:נ״ה

1 לשמות מטות אבותם, according to the names of the tribes of their respective fathers, etc. According to the view of Rabbi Yoshiah this verse merely demolishes the apparent meaning of the word לאלה. It tells us that the word לאלה was not meant to apply to the people counted in the wilderness of Moav but rather meant כאלה, that the people to be given land were to be כאלה like the ones who were counted at the Exodus, i.e. the ones who were twenty and over. Rabbi Yonathan, however, holds that although in the first instance the people who had been counted now were to inherit the land, they in turn would confer rights of inheritance on the people who had participated in the Exodus as has been explained in the Baraitha in the Sifri. The exact wording there is as follows: Assuming one (family) would inherit 1 acre and another (family) of the same בית אב, branch of this tribe, 3 acres by applying the yardstick of the number of 20 year olds in the families at present, then the combined amount would be inherited by the previous generation (the dead) of this family. This inheritance in turn would now be allocated on an equal basis to the younger generation so that both families of the younger generation would receive 2 acres although one family was more numerous than the other at this time. [Our example assumes that there had been only two sons of the family which participated in the Exodus. Ed.] By following this approach the word ינחלו "they will inherit" at the end of verse 35 becomes very relevant as it refers to the people who had now been counted not inheriting now, but only via their fathers. This also explains why the Torah wrote תחלק הארץ, "the land will be divided," instead of writing "they will divide the land." The same consideration also prompted the Torah to write the words תרבה נחלתו in the future tense. Also the expression יותן נחלתו "his inheritance will be given," instead of יקח נחלתו "he will take his inheritance" points to the explanation of Rabbi Yonathan that the generation of the people who left Egypt were the key to the distribution of the land is correct. Our verse teaches then that up until this point the Torah speaks about what Joshua is to do at the time he will make the Israelites inherit the land. From this point on, however, the people who do the inheriting have to consider their share in terms of לשמות מטות אבותם, according to the names of the members of the family groups who had left Egypt.