Deuteronomy 21:15-16

New American Standard Bible

¹⁵ “If a man has two wives, the one loved and ^(A)the other ^[a]unloved, and both the loved and the ^[b]unloved have borne him sons, and the firstborn son belongs to the ^[c]unloved, ¹⁶ then it shall be on the day that he wills what he owns as an inheritance to his sons, he is not allowed to treat the son of the loved wife as the firstborn, ^[d]at the expense of the son of the ^[e]unloved, who actually is the firstborn son.