As David Letterman winds down his tenure on The Late Show, he's bringing on some of his all-time favorite musical guests – and that certainly includes folk singer-songwriter and former Drive-By Truckers member Jason Isbell.

Along with his wife, Amanda Shires, Isbell stopped by the show Friday night (April 24) and performed a delicate cover of Warren Zevon's "Mutineer." Watch the video above. Of course, Zevon himself was a close friend of Letterman's and a big part of the show's musical legacy: Zevon was a frequent guest and even occasionally served as substitute band leader. Zevon performed "Mutineer" on the show during his final appearance with Letterman in 2002, a year before he succumbed to cancer. Watch that touching video below.

After the cover by Isbell and Shires, Letterman offered a heartfelt thank you and appeared genuinely touched. He joked that he assumed Isbell's upcoming album, Something More Than Free, would be available for free. Isbell laughed and said, "Almost."

Warren Zevon – "Mutineer" on the Late Show with David Letterman in 2002