'Birthright' in the Bible

And Jacob said, Sell me now thy birthright.

And Esau said, Behold, I am going to die, and of what use can the birthright be to me?

And Jacob said, Swear unto me now. And he swore unto him, and sold his birthright to Jacob.

And Jacob gave Esau bread and the dish of lentils; and he ate and drank, and rose up and went away. Thus Esau despised the birthright.

And he said, Is it not therefore he was named Jacob, for he has supplanted me now twice? He took away my birthright, and behold, now he has taken away my blessing. And he said, Hast thou not reserved a blessing for me?

And they sat before him, the firstborn according to his birthright, and the youngest according to his youth; and the men marvelled one at another.