It's my claim, but i have made some reservations about its validity.
I loaded it (approx 0:20) into my sampler and played it over the the glaziers track and managed to find the right key, sound and tempo, but there are some vocals on the part i tried, which shouldnt be there.
I have made a really quick demonstration below (link), and excuse the poor quality, i didnt have time to do it properly. its mainly for you to get an impression of what I mean.
http://picosong.com/CUME/
This leads us to a couple of different conclusions:
1. rza stitched together different parts of the track, thus getting rid of the vocals
2. it was sampled from different version of the same track, perhaps stereo or mono (which is often the case)
3. the vocals could somehow be filtered out using some filter i havent got access to
4. its not this sample.