Esau said, “Is he not rightly named Jacob? For he has supplanted me these two times. He took away my birthright; and behold, now he has taken away my blessing.” Then he said, “Have you not reserved a blessing for me?”
The sons of Reuben the first-born of Israel (for he was the first-born; but because he polluted his father's couch, his birthright was given to the sons of Joseph the son of Israel, so that he is not enrolled in the genealogy according to the birthright;
then on the day when he assigns his possessions as an inheritance to his sons, he may not treat the son of the loved as the first-born in preference to the son of the disliked, who is the first-born,
but he shall acknowledge the first-born, the son of the disliked, by giving him a double portion of all that he has, for he is the first issue of his strength; the right of the first-born is his.