David Letterman, who’s never been shy about his feelings about Jay Leno, gives his old rival a classic back-handed compliment in his upcoming interview with Oprah Winfrey on her OWN program Oprah’s Next Chapter. “He’s an unusual fellow. I’ve never met anyone quite like Jay,” Letterman says in the released promo clip. “And I will say, and I’m happy to say, that I think he is the funniest guy I’ve ever known. Just flat out, if you go to see him do his nightclub act, just the funniest, the smartest, a wonderful observationist and very appealing as a comic. Therefore, the fact that he is also maybe the most insecure person I have ever known — I could never reconcile that.” Ouch! Letterman’s statement on Leno was actually in response to Winfrey’s question when the duo’s rivalry began (not when Leno got the Tonight Show gig according to Letterman), so we’ll presumably find that out. The interview, which comes on the heels of fellow latetnight comedian Jimmy Kimmel bashing Leno, airs January 6. Winfrey, Letterman and Leno have a history together — the trio did the famous Late Night With David Letterman Super Bowl promo, which aired at the height of NBC’s Leno-Conan debacle of 2010. (you watch it again below)