Every instrument explanatory of any deed or other writing purporting to be a conveyance but intended to be defeasible or as security for the payment of money, shall be deemed a part thereof, and must be filed and recorded therewith; and unless such instruments are so filed and recorded together, they and each of them shall have no other effect than an unrecorded mortgage, and the recording of the principal instrument shall secure no rights to the holder thereof. R.L. 1910, § 1157.
Oklahoma Legal Code