Okla. Stat. tit. 42, § 42-27: Waiver of vendor's lien

Where the buyer of real property gives to the seller a written

contract for payment of all or part of the price, an absolute

transfer of such contract by the seller, waives his lien to the

extent of the sum payable under the contract, but a transfer of such

contract in trust to pay debts, and return the surplus, is not a

waiver of the lien.