Okla. Stat. tit. 58, § 286

The discharge or bequest in a will of any debt or demand of the testator against the executor named, or any other person, is not valid against the creditors of the decedent, but is a specific bequest of the debt or demand. It must be included in the inventory, and, if necessary, applied in the payment of the debts. If not necessary for that purpose, it must be paid in the same manner and proportion as other specific legacies.