16 when he wills his property to his sons, he must not give the rights of the firstborn to the son of the wife he loves in preference to his actual firstborn, the son of the wife he does not love.
16 Then it shall be, when he maketh his sons to inherit that which he hath, that he may not make the son of the beloved firstborn before the son of the hated, which is indeed the firstborn:
16 then on the day when he assigns his possessions as an inheritance to his sons, he may not treat the son of the loved as the firstborn in preference to the son of the unloved, who is the firstborn,
16 at the time he divides the inheritance with his sons he must not treat the son of the loved wife as the firstborn, cutting out the son of the hated wife, who is the actual firstborn.
16 then it shall be, on the day he bequeaths his possessions to his sons, that he must not bestow firstborn status on the son of the loved wife in preference to the son of the unloved, the true firstborn.
16 When the man divides his inheritance, he may not give the larger inheritance to his younger son, the son of the wife he loves, as if he were the firstborn son.
Matthew Henry's Commentary on Deuteronomy 21:16
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.