Deuteronomy 21:16

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:

Cross-reference

In 1 Chronicles 5:2, Joseph (son of loved wife) received the birthright over firstborn Reuben—directly opposing the law's prohibition here.

In 2 Chronicles 11:19-22, Rehoboam made his loved wife's son chief—a clear violation of the inheritance law forbidding such favoritism.

In 2 Chronicles 21:3, Jehoshaphat gave the kingdom to firstborn Jehoram—faithfully following the law's command to honor the firstborn.

In Hebrews 12:16, Esau sold his birthright, highlighting its value that this law aims to protect from arbitrary transfer.

In 1 Chronicles 26:10, Hosah appointed a non-firstborn as leader—similar bypassing of primogeniture, though for appointments not inheritance.