In proving any written instrument or contract to which there is a subscribing witness, or to which there are two or more subscribing witnesses, it shall not be necessary to call any such witness or witnesses, but the instrument or contract may be proved, except for purposes of filing or recording the same, by the evidence by which an instrument or contract to which there is no subscribing witness may be proved. It shall not be permissible, in any case, to prove such instrument or contract by proof of the handwriting of the subscribing witness or witnesses, but in all cases such instrument or contract must be proved in the same manner as one having no subscribing witness whatever.
N.D.C.C. § 31-08-02