Albert Barnes Commentary Matthew 19:8

"He saith unto them, Moses for your hardness of heart suffered you to put away your wives: but from the beginning it hath not been so." — Matthew 19:8 (ASV)

He says to them, and so on. Jesus admits that this was allowed, but still He contends that this was not the original design of marriage. It was only a temporary expedient, growing out of a particular state of things, and not designed to be perpetual. It was because of the hardness of their hearts.

Moses found the custom in use. He found a hard-hearted and rebellious people. In this state of things, he did not consider it prudent to forbid a practice so universal; however, it could be regulated. Instead of allowing the husband to divorce his wife in a passion, Moses required him to give her a written document so that he might take time to consider the matter, thus making it probable that divorces would be less frequent. He was also required to sit down deliberately, examine the situation, and probably bring the case before some scribe or learned man to write a divorce in the legal form.

In this way, there might be an opportunity for the matter to be reconciled and the man to be persuaded not to divorce his wife. This, says our Savior, was a permission growing out of a particular state of things and designed to remedy a prevailing evil. But at first, it was not so. God intended that marriage should be between one man and one woman, and that they were only to be separated by the appointment of Him who had formed the union.

Hardness of your hearts. He speaks here of His hearers as a part of the nation. He refers to the hardness of you Jews. This is similar to when we say, "We fought with England and gained our independence," meaning we, the American people, even though it was done by our fathers. Therefore, He does not mean to say that this was done because of the people He addressed at that moment, but rather because of the national hardness of heart—the cruelty of the Jewish people as a people.