Genesis 25:29-33

Now Jacob cooked a stew; and Esau came in from the field, and he was weary. And Esau said to Jacob, “Please feed me with that same red stew, for I am weary.” Therefore his name was called Edom. But Jacob said, “Sell me your birthright as of this day.” And Esau said, “Look, I am about to die; so what is this birthright to me?” Then Jacob said, “Swear to me as of this day.” So he swore to him, and sold his birthright to Jacob.