Genesis 25:31-34

But Jacob said, “First sell me your birthright.” Esau said, “Behold, I am about to die; so of what use then is the birthright to me?” And Jacob said, “First swear to me”; 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 on his way. Thus Esau despised his birthright.