All sales of real estate of wards must be for cash, or for part cash and part deferred payments not to exceed ten (10) years, bearing interest from date of sale as, in the discretion of the court, is most beneficial to the ward. A guardian making a sale of real property shall demand and receive from the purchasers a note and mortgage on the real estate sold, with such additional security, if any, as the court deems necessary and sufficient to secure the faithful payment of the deferred payments and the interest thereon.
Okla. Stat. tit. 30, § 4-766