כִּי֩ אֶת־הַבְּכֹ֨ר בֶּן־הַשְּׂנוּאָ֜ה יַכִּ֗יר לָ֤תֶת לוֹ֙ פִּ֣י שְׁנַ֔יִם בְּכֹ֥ל אֲשֶׁר־יִמָּצֵ֖א ל֑וֹ כִּי־הוּא֙ רֵאשִׁ֣ית אֹנ֔וֹ ל֖וֹ מִשְׁפַּ֥ט הַבְּכֹרָֽה׃ (ס)
반드시 그 미움을 받는 자의 아들을 장자로 인정하여 자기의 소유에서 그에게는 두 몫을 줄 것이니 그는 자기의 기력의 시작이라 장자의 권리가 그에게 있음이니라
Kedushat Levi
Genesis 49,4. “unstable as water, you will not enjoy the additional portion due to the firstborn;” How could Yaakov deliberately ignore the commandment not to deprive even the son of a wife who was hated of the rights accruing to him as a firstborn? (Deut. 21,17) Nachmanides writes concerning this problem that Yaakov penalized Reuven in accordance with the nature of his sin.
Personally, I believe that Yaakov saw in his prophetic vision of the future what the Torah calls גוי וקהל גויים, “a nation and a community of nations,” (Genesis 35,11) a promise made to him by G’d at a time when he personally had concluded siring children, that another two tribes would become part of the Jewish people, so that in order for the number of tribes not to exceed the number 12, “something had to give.” He had not been aware that these two “tribes” would not be sons, but grandsons of his. The only way he was able to explain G’d’s promise of two more tribes was by assuming that an existing one would prove unworthy.
Personally, I believe that Yaakov saw in his prophetic vision of the future what the Torah calls גוי וקהל גויים, “a nation and a community of nations,” (Genesis 35,11) a promise made to him by G’d at a time when he personally had concluded siring children, that another two tribes would become part of the Jewish people, so that in order for the number of tribes not to exceed the number 12, “something had to give.” He had not been aware that these two “tribes” would not be sons, but grandsons of his. The only way he was able to explain G’d’s promise of two more tribes was by assuming that an existing one would prove unworthy.