If a man have two wives This practice, though tolerated, is not hereby made lawful; but only provision is made for the children in that case. Hated Comparatively, that is, less loved.
Related Commentaries of Deuteronomy 21:15
Deuteronomy 21:15
15 If a man have two wives, one beloved, and another hated, and they have born him children, both the beloved and the hated; and if the firstborn son be hers that was hated: