Talmud zu Bereschit 27:15

HALAKHAH: [“The only difference between a public altar and a private altar, etc.”] Rebbi Joḥanan spent three years that he did not visit the house of assembly because of pain. At the end Rebbi Eleazar saw in his dream: Tomorrow Sinai will come down and bring a new insight. He came and said before them, from where is this truth verified that divine service is by firstborns?⁴⁷⁰Mishnah Zevaḥim14:4: Before the Tabernacle was erected private altars were permitted and the service was in the hands of the firstborn. From this verse⁴⁷¹Num. 3:13. The reference is to the later part of the verse, I sanctified for Me every firstborn in Israel., for Mine is every firstborn; on the day when I smote every firstborn in the Land of Egypt, etc. And it is written⁴⁷²Ex. 12:12. The firstborn were sanctified to God because the gods of Egypt were destroyed., and on all gods of Egypt I shall pass judgment, etc. Before that what were they doing? Rebecca took the desirable garments of her older son Esaw, which were with her in the house⁴⁷³Gen. 27:15.. What are “the desirable”? That he was acting as High Priest. Rebbi Levi said, the Eternal broke the staff of the evildoers⁴⁷⁴Is. 14:5., these are the firstborn who were the first to sacrifice to the Calf⁴⁷⁵Num. rabba 4(5)..