Matthew 19:3

And there came unto him Pharisees, trying him, and saying, Is it lawful for a man to put away his wife for every cause?

The Pharisees were not asking for information but in the hope of opening up a conflict between the teachings of Moses and those of Christ. This is actually an unconscious admission on their part of the weakness in Moses' permission of divorce because, if Christ had agreed with Moses, they would have had no case. The proof of weakness in Moses' position is that they instinctively knew Christ would not agree with it! Why? They knew in their hearts that Moses was wrong (or at least partially so); and, intuitively, those evil men recognized in Christ a higher purity and knowledge than existed in Moses and decided to take advantage of it if they could.