'Birthright' in the Bible

Then Jacob said, "Sell me your birthright {first}."

And Esau said, "Look, I am going to die; now what [is] this birthright to me?"

Then Jacob said, "Swear to me {first}." And he swore to him, and sold his birthright to Jacob.

Then Jacob gave Esau bread, and thick lentil stew, and he ate and drank. Then he got up and went away. So Esau despised his birthright.

Then he said, "{Isn't that why he is named Jacob}? He has deceived me these two times. He took my birthright and, look, now he has taken my blessing!" Then he said, "Have you not reserved a blessing for me?"

And they were seated before him [from] the firstborn according to his birthright [to] the youngest according to his youth. And the men {looked at one another} amazed.