“He saith unto them, Moses because of the hardness of your hearts suffered you to put away your wives: but from the beginning it was not so.”
King James Version (KJV)
Mt 19:8 Moses, for the hardness of your heart. Moses "suffered" some things that were not right on account of "the hardness of your heart", a low state of morals. A people cannot be lifted from moral depravity to a high standard at once. Hence the law permitted some things that were below the perfect standard of Christ. From the beginning. In the beginning there was no divorce and no polygamy. The first polygamist was the race of Cain (Ge 4:19).