Contrary to what the promo clips for Jay-Z's 'Magna Cart Holy Grail' would have us believe master producer did not in work on the album.

Rick Rubin is a living legend in the music industry. The co-founder of Def Jam records, his catalog ranges from Public Enemy to Adele, Johnny Cash to Kid Rock. Because his work tends to be behind the scenes, Rubin's name often does not show up in the spotlight. However, in the last month, his name has become a buzzword thanks to his apparent contributions to two of hip-hop's biggest releases in 2013.

After working on Kanye West's 'Yeezus' and getting interviewed by multiple outlets regarding his contributions to that project, Rubin was spotted in a Samsung commercial which announced Jay-Z's upcoming 'Magna Carta Holy Grail' album. From the commercials and pictures that have surfaced, it seemed as though Rubin was very much a part of the creative process for the album, as he's shown relaxed and even lying down on a couch barefoot.

However, Rubin himself just informed XXL today that he actually did not contribute anything to the album. He said that Jay-Z had invited him to the studio to hear some of the music, and since the studio session at the time was being filmed, he became a part of the documentary that resulted. However, after listening to the album, he decided that he would not be comfortable contributing to it. According to Rubin, Jay's album was a more traditional hip-hop album, something drastically different from 'Yeezus,' which he had just finished working on.

But what exactly would Rubin's contribution to Jay's album have been had he been a part of the process? According to someone who had previously worked with Rubin, things wouldn't have been substantially different.

During the question and answer part of an appearance in Dallas, Texas on November 18, 2011, Slipknot's front man Corey Taylor was asked about working with Rick Rubin for Slipknot's 'Vol. 3 (The Subliminal Verses).' "That's a dangerous, dangerous question," Taylor replied, before cutting right into the heart of the matter. According to Taylor, Rubin would come into the studio during those sessions for about 45 minutes a week. He would proceed to lie on a couch, and have the engineer play the music that had been worked on. After a few moments he would ask the band to re-record a certain portion. Taylor's full answer is below.

The Slipknot frontman concluded by saying simply, "Rick Rubin is overrated, he is overpaid, and I will never work with him again as long as I f--king live."

It is important to note that Taylor's account of working with Rubin contradicts what other members of the band have said about the experience. In an interview with Revolver magazine, percussionist Shawn Crahan called Rubin "the oracle" while lauding him for helping the band rebuild their relationship. In the same interview, guitarist Jim Root called 'Vol. 3' his "favorite record" the band had done, adding that "Rubin was very attentive to what we needed as a band."

With all this said, it is not likely that these recent comments will not even leave a dent on Rubin's rich legacy. But still, it makes one wonder: what is it really like working with the bearded one at this stage in his career?