Mat 23:2 The scribes and the Pharisees sit in Moses' seat:
Mat 23:3 All therefore whatever they bid you observe, [that] observe and do; but do not after their works: for they say, and do not.

It is interesting that Christ never teaches anything but respect for existing authority. Well, perhaps "respect" is too strong a word. Recognition of authority may be closer to the idea. At the same time Christ also teaches that civil institutions are never the source of either moral authority or true justice. This verse is a perfect example of his philosophy.

Here, he doesn't exactly say to "obey" authority. The word he uses means "to give heed to" and "to guard." You might translate it as "What out for whatever they tell you to do and do it." It is almost like a warning.

At the same time, Christ criticizes what those in authority produce. "Don't do what they do."

"Seat" is from kathedra, which means "a chair," "a seat" "a sitting position," and "a throne," is used to denote a position of power.

"Sit" is from kathizô, which means "to make sit down," "to seat," "to place," "to sit," "to recline at meals," and "to settle."

"Observe" is from têreô, which means "to watch over," "to guard," "to take care of," "to give heed to," "to keep," and "to observe."

"Done" is from poieo, which means "to make," "to produce," or "to do."

"Works" is from ergon, which means "work," "deeds," "[peaceful] contests," "works of industry," "deed," "property," "wealth," and "occupation."