Oklahoma constitution
Article V: legislative power
Section 23

No member of the Legislature shall, during the term for which he was elected, be appointed or elected to any office or commission in the State, which shall have been created, or the emoluments of which shall have been increased, during his term of office, nor shall any member receive any appointment from the Governor, the Governor and Senate, or from the Legislature, during the term for which he shall have been elected, nor shall any member, during the term for which he shall have been elected, or within two years thereafter, be interested, directly or indirectly, in any contract with the State, or any county or other subdivision thereof, authorized by law passed during the term for which he shall have been elected.