American comedian and actor Eddie Murphy has finally revealed why he refused to play Bill Cosby on "Saturday Night Live's" 40th anniversary show.

Murphy did not perform at all during "SNL 40," rather opting for a brief "thank you" speech that was shorter than Chris Rock's introduction of him.

Murphy's appearance was a big disappointment. The comedian stated that the sketch Norm Macdonald wrote "was hysterical." After the program, former SNL member Norm MacDonald revealed in several now-deleted tweets that a sketch poking fun at Cosby was written for Murphy.

In spite of Murphy's hilarious imitations of Cosby in the past, and their somewhat disputative relationship early in Murphy's career, Eddie declined and the role was filled by Kenan Thompson.

Murphy said he turned down the impression because "It's frightful." In the end, he could not do it. "It's disgusting," he said.