[Avodah] gentiles and tefillin

[Arie Folger]

The Radvaz on Rambam, Hil. Melakhim 10:10 comments that, while acc. to Rambam, 
gentiles may voluntarily fulfil mitzvot in order to merit sechar, 
nonetheless, Radvaz considers that we should not permit gentiles to fulfil 
such kinds of mitzvot that require "qedushah vetaharah," such as Tefillin, 
Sefer Torah and Mezuzot.

Do some members of this august company know of other sources that discuss this 
matter, especially as it applies to tzitzit and tefillin?
-- 
Arie Folger
http://www.ariefolger.googlepages.com