15 "If a man has two wives, one loved and the other unloved, and they have borne him children, both the loved and the unloved, and if the firstborn son is of her who is unloved,

Matthew Henry's Commentary on Deuteronomy 21:15

Commentary on Deuteronomy 21:15-17

(Read Deuteronomy 21:15-17)

This law restrains men from disinheriting their eldest sons without just cause. The principle in this case as to children, is still binding to parents; they must give children their right without partiality.