When a man has two wives, one loved and the other unloved, and they have borne him children, both the loved and the unloved, and the first-born son is of her who is unloved,”
And she conceived again and bore a son, and said, “Because יהוה has heard that I am unloved, He gave me this son too.” And she called his name Shim‛on.
then it shall be, on the day he makes his sons to inherit his possessions, he is not allowed to treat the son of the beloved wife as first-born in the face of the son of the unloved, who is truly the first-born.