Kommentar zu Bereschit 48:6

Although the Land was divided according to the number of heads — as it is written, (Numbers 26:54) “To the more numerous thou shalt give a larger inheritance” — and each person had an equal share except those who were first-born sons (and these received a double share), yet only these of Joseph’s sons bore the name of “tribe” when it became a matter of casting lots for the partition of the land according to the number of the tribes (cf. Numbers 26:55), and of appointing princes to the various tribes and of assigning banners to each of them.

AND THE CHILDREN THAT WERE BORN TO YOU AFTER THEM. “If you beget any more children, they will not be numbered among my sons, but they will rather be included among the tribes of Ephraim and Menasheh. Nor shall they have a name amongst the tribes as far as inheritance in the Land of Israel is concerned.” Now even though the Land of Israel was divided according to the number of persons, as it is written, To the more thou shalt give the more inheritance,¹⁵Numbers 26:54. and each person received an equal share except for the first-born, who received a double share,¹⁶Deuteronomy 21:17. nevertheless only these sons were designated as “tribes.” This is the language of Rashi.
Now this is not correct, for if so,¹⁷If, as Rashi says, Joseph’s designation as firstborn meant only that Joseph’s two sons shall be counted as separate tribes, but not that they shall receive a double share in the Land, then it follows that, etc. then Jacob’s granting of the birthright to Joseph was just nominal, its only effect being that Joseph’s sons would be called “tribes,” whereas the verse states, in their inheritance.¹⁸At the end of the verse before us: And the children that were born to you after shall be counted to you; they shall be called after the name of their brethren ‘in their inheritance.’ This indicates that the two sons of Joseph were to be given the extra right of the firstborn in the matter of inheritance. In the Gemara,¹⁹Horayoth 6b. the Sages have said: “I have likened Ephraim and Menasheh to Reuben and Simeon with respect to the matter of inheritance, but not with respect to other matters,”²⁰As, for example, the case of a Sin-offering which is brought by the great Sanhedrin for an erroneous decision, followed by most of the tribes even though they did not constitute an actual majority of the entire population. In that case Ephraim and Menasheh are considered part of the tribe of Joseph. as is stated in Tractate Horayoth.¹⁹Horayoth 6b. Our Rabbis have mentioned in many places²¹Baba Bathra 123a. that Joseph was the first-born as far as inheritance was concerned, and that he received a double share in the Land, as is the rule of every first-born,¹⁶Deuteronomy 21:17. but not that his being first-born consisted merely of his sons being called “tribes,” as the Rabbi [Rashi] would have it.
From this we further learn that the Land was not divided among all the tribes of Israel according to their populations for if so, what was the significance of this primogeniture with respect to inheritance? If we would say it meant that each and every individual offspring of Joseph was given double that of each person of all other tribes, this is not mentioned at all in Scripture, and we do not find Jacob giving the birthright to Joseph except by what he said here, As Reuben and Simeon shall they be to me,,²²Verse 5 here. and based upon this, Scripture states, His [Reuben’s] birthright was given to the sons of Joseph the son of Israel.²³I Chronicles 5:1. If so, then Ephraim and Menasheh were fully considered as two tribes, and it was this which constituted Joseph’s birthright, and the words of the Sages indeed corroborate this everywhere.
Thus the matter is not at all as the Rabbi²⁴Rashi. Rashi’s premise that the Land was divided according to population is disputed by Ramban. Since, according to Ramban, each tribe received an equal portion, he proceeds to differ with Rashi and says that Joseph received twice as much land as any other tribe since Ephraim and Menasheh were considered separate tribes. stated it. Instead, the Land of Israel was divided according to tribes. They made twelve equal parts of it, with Simeon, the least populous of the tribes, taking a share equal to that of Judah, the most populous of the tribes, and thus, Ephraim and Menasheh took exactly the same amount of land as Reuben and Simeon. This is the conclusion of the Gemara in the chapter, Yesh Nochalin.²⁵Baba Bathra 121b. Yesh Nochalin (“There are some that inherit,”) the eighth chapter of that tractate, deals with all problems of personal inheritance, as well as with the whole range of problems connected with the original division of the Land by Joshua. Scripture also states, Ye shall divide the land for inheritance according to the twelve tribes of Israel, Joseph receiving two portions.²⁶Ezekiel 47:13. So too does Onkelos say,²⁷In translating the blessing bestowed upon Joseph by Jacob. Further, 49:22. “Two tribes shall come forth from his sons. They shall receive chulka ve’achsanta (portion and inheritance),” which means that they shall be equal to the other tribes with respect to inheritance received. Now chulka (portion) refers to the extra share of the first-born, and achsanta (inheritance) refers to ordinary inheritance. In the verse stating, To the more thou shalt give the more inheritance, and to the fewer thou shalt give the less inheritance,²⁸Numbers 26:54. This verse, which seems to indicate that the Land was divided according to population, as Rashi taught, is explained by Ramban as referring to the internal division within each tribe. Scripture refers to the paternal families mentioned there in the chapter.²⁹Ibid., Verses 8-50. Scripture is stating that the tribe divides its share of the land among the paternal families that left Egypt by giving a larger portion to a more populous family and a smaller portion to a less populous family, with the dead becoming heirs of the living, as is explained in the Sifre³⁰Sifre Pinchas 132. See also Ramban on Numbers 26:54. and is mentioned by Rashi in the Parshah of Pinchas.³¹Rashi, ibid. Thus the general principle with respect to Joseph was that he was the first-born as regards inheritance, and if, as mentioned in the Gemara,²⁵Baba Bathra 121b. Yesh Nochalin (“There are some that inherit,”) the eighth chapter of that tractate, deals with all problems of personal inheritance, as well as with the whole range of problems connected with the original division of the Land by Joshua. the land was divided according to the number of tribes, they gave the children of Joseph portions equal to those of Reuben and Simeon.
And even if we were to say that the land was divided according to the number of persons, as is apparent from the verse,³²To the more thou shalt give the more inheritance, etc. (Numbers 26:54.) then we would say that they gave them double portions commensurate with their numbers — an ordinary share as large as all the other people, and a second portion for the birthright. In that case, the meaning of Jacob’s words, As Reuben and Simeon shall they be to me,²²Verse 5 here. is that they should receive as many shares as twice their number of people. But that Joseph should be as the other tribes with respect to inheritance, with the birthright consisting of his two sons being called “tribes,” as the Rabbi³³Rashi. In his commentary to Numbers 26:54, Ramban further discusses this problem at great length. stated, this is impossible under any circumstance.

ומולדתך, your children or grandchildren who will be born or have been born after my arrival in Egypt (during the last 17 years). על שם אחיהם יקראו, they will have the same status as their brothers, i.e. they will not each be considered as the founding father of one of the tribes, but בתי אבות, heads of family groupings within the tribe they belong to (Menashe or Ephrayim). All the seventy souls included in the count of people descending to Egypt with Yaakov, whether his sons or his grandsons, became the heads of such family groups. And this was of relevance when the land of Israel was distributed by Joshua. The Talmud Baba Batra 118 discusses this in detail, basing itself on Numbers 26,21 mentioning such families as Peretz and Chetzron, etc., as well as the members of the family of Elon and Ard and Naamon mentioned in verses 40 and 53-55 respectively in that same chapter. What applied in those situations would also apply to children of Joseph born after Yaakov’s arrival in Egypt.