'Birthright' in the Bible

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?”

And Jacob said, “First swear to me”; so he swore to him, and sold his birthright to Jacob.

Then Jacob gave Esau bread and lentil stew; and he ate and drank, and rose and went on his way. Thus Esau despised his birthright.

Then he said, “Is he not rightly named Jacob, for he has supplanted me these two times? He took away my birthright, and behold, now he has taken away my blessing.” And he said, “Have you not reserved a blessing for me?”

Now they were seated before him, the firstborn according to his birthright and the youngest according to his youth, and the men looked at one another in astonishment.