15 "If a man has two wives , the one loved and the other unloved , and both the loved and the unloved have borne him sons , if the firstborn son belongs to the unloved , 16 then it shall be in the day he wills what he has to his sons , he cannot e make the son of the loved the firstborn before e the son of the unloved , who is the firstborn . 17 "But he shall acknowledge the firstborn , the son of the unloved , by giving him a double portion of all that he has , for he is the beginning of his strength ; to him belongs the right of the firstborn .

Matthew Henry's Commentary on Deuteronomy 21:15-17

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.