Albert Barnes Commentary Matthew 23:3

"all things therefore whatsoever they bid you, [these] do and observe: but do not ye after their works; for they say, and do not." — Matthew 23:3 (ASV)

All therefore whatever, and so on: that is, all that they teach 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 traditions (Matthew 15:1–6).

They say, and do not. The interpretation they give to the law is for the most part 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; but they are rather to obey the law of God than to shape their lives by the example of evil men.