Suppose a man has two wives. He loves one but not the other. And both of them have sons by him. But the oldest son is the son of the wife the man doesn’t love.
She became pregnant again. She had a son. Then she said, “The Lord heard that Jacob doesn’t love me very much. That’s why the Lord gave me this one too.” So she named him Simeon.
Someday he’ll leave his property to his sons. When he does, he must not give the rights of the oldest son to the son of the wife he loves. He must give those rights to his oldest son. He must do it even though his oldest son is the son of the wife he doesn’t love.