Apostolic Constitutions, Book VII 14
1You shall hate all hypocrisy; and whatsoever is pleasing to the Lord, that shall you do. By no means forsake the commands of the Lord. But you shall observe what things you have received from Him, neither adding to them nor taking away from them. For you shall not add unto His words, lest He convict you, and you become a liar. You shall confess your sins unto the Lord your God; and you shall not add unto them, that it may be well with you from the Lord your God, who wills not the death of a sinner, but his repentance.