Production of title-deeds of witness not a party.

No witness who is not a party to a suit shall be compelled to produce his title-deeds to any property, or any document in virtue of which he holds any property as pledgee or mortgagee or any document the production of which might tend to criminate him, unless he has agreed in writing to produce them with the person seeking the production of such deeds or some person through whom he claims.