“But Jacob said, “First sell me your birthright.” Esau said, “Behold, I am about to die; so of what use then is the birthright to me?”” Gen. 25:31-32
This passage is often read without understanding as to what the birthright is, so any significance is usually missed. Instead we are left with an overly dramatic Esau, and confusion about why Jacob would want something he can’t really seem to have, but somehow gets.
The birthright is not merely ‘being born first’, but rather has several aspects. In the familial aspect, we see that Isaac favored Esau (25:28), and the firstborn had a preferred place as planned successor of the head of the household.
However there was also a spiritual aspect of the birthright, a responsibility that comes with being born first. The first child was like the firstfruits of an offering; the sacrificial responsibilities fell to Esau (Rashi, also, midrash), and so in this way he could be viewed as the high-priest of the family, and a type of the Levitical priesthood to come.
Knowing what we know later of the Levitical priesthood and the seriousness of the task, it is fair to speculate that perhaps Esau was not merely exaggerating that he was going to die because he was hungry – he may have known his own heart and felt he was not prepared to live such a life of service to God. Jacob, on the other hand, felt he was able to perform these responsibilities. When it tells us in v. 27 that Jacob ‘lived in tents’, the rabbis say this refers to the tents where the teachings of God took place, hearkening back to ‘dwelling in the tents of Shem’ from the Noah story. Thus Jacob took God seriously, and perhaps Esau did not, and he knew.
We often forget that others were following God at this point, not just Isaac and his family. All the way back in Genesis 14, we see Melchizedek seemingly come out of nowhere, but yet he is a priest of God Most High, long before any official temple and before Levitical law was instituted in the scriptures.