Deuteronomy 21:14-16

Young's Literal Translation

¹⁴ `And it hath been -- if thou hast not delighted in her, that thou hast sent her away at her desire, and thou dost not at all sell her for money; thou dost not tyrannize over her, because that thou hast humbled her.

¹⁵ `When a man hath two wives, the one loved and the other hated, and they have borne to him sons (the loved one and the hated one), and the first-born son hath been to the hated one;

¹⁶ then it hath been, in the day of his causing his sons to inherit that which he hath, he is not able to declare first-born the son of the loved one, in the face of the son of the hated one -- the first-born.