The Commissioner of Revenue, before entering upon the discharge of his duties, shall take, subscribe, and file with the Secretary of State the following special oath of office in addition to the general oath of office prescribed for public officers by the Constitution of Alabama: “I, _____, do hereby solemnly swear that I will faithfully, impartially perform the duties of office as Commissioner of Revenue, to which I have been appointed and which I now assume, without fear or favor, bias, or thought of personal gain or advantage, to the best and utmost of my ability, capacity, and power.” This oath shall be taken before any officer qualified to administer oaths in the State of Alabama and thereupon shall be filed with the Secretary of State.