All, therefore, whatsoever ... - That is, all that they teach that is consistent with the Law of Moses - all the commands of Moses which they read to you and properly explain. The word “all” could not be taken without such a restriction, for Christ himself accuses them of teaching many things contrary to that law, and of making it void by their traditions, Matthew 15:1-6.
They say, and do not - The interpretation which they give to the law is in the main correct, but their lives do not correspond with their teaching. It is not the duty of people to imitate their teachers unless their lives are pure; they are to obey the law of God, and not to frame their lives by the example of evil people.