Okla. Stat. tit. 60, § 140

Where a trust is created to receive the rents and profits of real property, and no valid direction for accumulation is given, the surplus of such rents and profits, beyond the sum that may be necessary for the education and support of the person for whose benefit the trust is created, is liable to the claims of the creditors of such person, in the same manner as personal property which cannot be reached by execution.