"Truth that is not experienced is no better than error, and may be fully as dangerous. The scribes who sat in Moses' seat were not the victims of error; they were the victims of their failure to experience what they taught."
A W Tozer
While you can get specifics in Exodus Chapter 18 I believe this is referring to the Laws of Moses and the subsequent corruption that Israels leadership fell into. It would seem that they knew the letter of the law but had no concept of the heart in which it was given. Jesus Himself would take the Old Covenant that the religious folks made bondage of and use it to demonstrate God's love and the freedom found in His Word.
2Co 3:6 Who also hath made us able ministers of the new testament; not of the letter, but of the spirit: for the letter killeth, but the spirit giveth life.