Nas' Mass Appeal label is set to release a posthumous J Dilla vocal album titled The Diary, on April 15. Leading up to tomorrow's release, Nas has previewed 'The Sickness,' which features he and Dilla rapping on a Madlib beat. The single was recorded in 2001, with Nas' verse added earlier this year.

"May J Dilla continue to Rest in Power in Hip Hop Heaven for eternity," Nas said in a statement. "Honored to play a part in his works and honored to be a part of this song. He shines down on us with while we get to enjoy his Diary Of J Dilla album. His word ring loud on this one. Salute to all those who collaborated on this piece. Salute to Detroit and his family."