Mo. Rev. Stat. § 287.600: Oath of office.

Each person appointed to office of employment by the division shall, before entering upon his duties, take and subscribe to an oath or affirmation to support the Constitution of the United States, and of this state, and to faithfully and honestly discharge the duties of such office or employment. Each person appointed to office by the division shall give his whole time to his duties, nor shall he serve on any committee of any political party.