the hardness of your hearts - looking to your low moral state, and your inability to endure the strictness of the original law.
suffered you to put away your wives - tolerated a relaxation of the strictness of the marriage bond - not as approving of it, but to prevent still greater evils.
But from the beginning it was not so - This is repeated, in order to impress upon His audience the temporary and purely civil character of this Mosaic relaxation.