It is the duty and obligation of every licensee to make full disclosure to the Board at a hearing before the Board or to the stewards at a hearing before the stewards of any knowledge he possesses of a violation of any racing law or of the rules and regulations of the Board, and no person may refuse to testify before the stewards at any hearing on any relevant matter within the authority of the stewards, except in the proper exercise of a legal privilege, nor shall any person testify falsely before the stewards.