Genesis 25:29-33

Once when Jacob was cooking stew, Esau came in from the field, and he was exhausted. And Esau said to Jacob, “Let me eat some of that red stew, for I am exhausted!” (Therefore his name was called Edom.) Jacob said, “Sell me your birthright now.” Esau said, “I am about to die; of what use is a birthright to me?” Jacob said, “Swear to me now.” So he swore to him and sold his birthright to Jacob.