Genesis 25:29-33

29Jacob had cooked [reddish-brown lentil] stew [one day], when Esau came from the field and was famished;

30and Esau said to Jacob, “Please, let me have a quick swallow of that red stuff there, because I am exhausted and famished.” For that reason Esau was [also] called Edom (Red).

31Jacob answered, “First sell me your birthright (the rights of a firstborn).”

32Esau said, “Look, I am about to die [if I do not eat soon]; so of what use is this birthright to me?”

33Jacob said, “Swear [an oath] to me today [that you are selling it to me for this food]”; so he swore [an oath] to him, and sold him his birthright.