Dave Chappelle stopped by his friend John Mayer's concert Wednesday night to show the love to a friend they just lost -- Charlie Murphy.

Dave got onstage and praised Charlie for his friendship, comedy and storytelling. Then Dave told the crowd that Mayer's song, "You're Going to Live Forever in Me," always reminded him of his friend ... and Mayer performed it in tribute.

Mayer and Dave also reminded the crowd just how funny Murphy was by referencing one of his greatest lines ever from "Chappelle's Show."

Awesome and touching video.