Okla. Stat. tit. 58, § 178

When it is expressly provided in the will that no bond shall be required of the executor, letters testamentary may issue and sales of real estate be made and confirmed without any bond, unless the court, for good cause, require one to be executed; but the executor may, at any time afterward, if it appears from any cause necessary or proper, be required to file a bond as in other cases.