Matthew 23:3

All therefore whatsoever - That is, all those things which they read out of the law and prophets, and all things which they teach consistently with them. This must be our Lord's meaning: he could not have desired them to do every thing, without restriction, which the Jewish doctors taught; because himself warns his disciples against their false teaching, and testifies that they had made the word of God of none effect by their traditions. See Matthew 15:6, etc. Besides, as our Lord speaks here in the past tense - whatsoever they Have commanded, ὁσα ειπωσιν, he may refer to the teaching of a former period, when they taught the way of God in truth, or were much less corrupted than they were now.

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.

23:3 All things therefore - Which they read out of the law, and enforce therefrom.