Genesis 25:29-34 ESV
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. Then Jacob gave Esau bread and lentil stew, and he ate and drank and rose and went his way. Thus Esau despised his birthright.