Okla. Stat. tit. 16, § 16-11: Estoppel by receiving benefits

Any person or corporation, having knowingly received and

accepted the benefits or any part thereof, of any conveyance,

mortgage or contract relating to real estate shall be concluded

thereby and estopped to deny the validity of such conveyance,

mortgage or contract, or the power or authority to make and execute

the same, except on the ground of fraud; but this section shall not

apply to minors or persons of unsound mind who pay or tender back

the amount of such benefit received by themselves.