The Neptunes member has also revealed that he has been sworn to secrecy about speaking on their upcoming collaboration.
Speaking to MTV, Williams said: "The guy is 40 and had a No. 1 record, and he sold more records than anybody in hip-hop at the time his album came out. And it's still selling.
On the stars recording together, the producer said: "The one thing we're allowed to say about our new collaboration is he and I said that we're sworn to secrecy."