Genesis 25:27-34

When the boys grew up, Esau became a skillful hunter, a man of the open country; whereas Jacob was a simple man, who stayed among the tents. Isaac preferred Esau, because he was fond of game; but Rebekah preferred Jacob. Once, when Jacob was cooking a stew, Esau came in from the open country, famished. He said to Jacob, “Let me gulp down some of that red stuff; I am famished.” That is why he was called Edom. But Jacob replied, “First sell me your right as firstborn.” “Look,” said Esau, “I am on the point of dying. What good is the right as firstborn to me?” But Jacob said, “Swear to me first!” So he sold Jacob his right as firstborn under oath. Jacob then gave him some bread and the lentil stew; and Esau ate, drank, got up, and went his way. So Esau treated his right as firstborn with disdain.