Romans 2:21

you, then, who teach others, do you not teach yourself? You who preach against stealing, do you steal?

(v21, NIV)

The Jews have the law. They, having the law, are able to teach others. Apparently, they are a teacher of children and corrector of the foolish. If they can teach others, certainly they can teach themselves, can't they? How would you be able to teach others, yet not teach yourself? It's possible and we see it all the time. This is the person with the log in his own eye trying to take out the speck in his brother's eye. This is hypocrisy, and we see it all the time. It may even be evident in yourself.

The Jews have the law and boast in it. However, they are missing something because they in fact do not teach themselves. Paul poses this question, but it is meant to imply that the Jews in fact do not teach themselves. Even though they are a guide for the blind, they do not guide themselves. Beware of hypocrisy and beware especially of it in yourself. Sure, teach others; that is good. However, don't forget to teach yourself and live what you preach.