If you read the biblical story of Jacob and Esau you learn that their mother, Rebecca, favored Jacob (Isaac, their father, favored Esau). Isaac became blind and was going to bestow the blessing of birthright on Esau, since he was the elder. However, Rebecca convinced and helped Jacob trick Isaac into bestowing the birthright to Jacob. This infuriated Esau and he vowed to kill Jacob after Isaac died. Rebecca pleaded with Isaac to send Jacob away until Esau calmed down, so he did.