The Pharisees cannot say without further ado that Moses commanded divorce. He commanded that in the case of divorce a certificate of divorce should be given. In this command the permission to divorce is implied. This, however, is only an implicit concession, not a positive command. And so here they correctly answer, “Moses allowed a man to write a certificate of divorce and to send her away.” The two things are not the same, but by choosing the verb “to allow” it can be so formulated. For at issue is not the practice of the certificate of divorce but the question whether sending away is allowed. Yet, imperceptibly, the blood here is thicker than water. Giving an order (of the certificate of divorce) in cases where the woman is sent away does not imply that this sending away is now positively allowed rather than being tolerated from sheer necessity. The first conclusion is drawn by the Pharisees. Jesus teaches the second one, and that with reference to Scripture itself.1
4 They said, “Moses allowed a man to write a certificate of divorce and to send her away.”