It has been a week since the world lost Robin Williams, but David Letterman was off last week, so he had to hold off his tribute to a friend until last night on The Late Show. Letterman gave an emotional 10-minute tribute to Williams, who he knew for 38 years.

Letterman reminisced about those early days at the Comedy Store with countless other comics who have gone on to make history. As E! News notes, Letterman recalled that he and his friends didn’t often talk to Williams, since he seemed like such a funny source of energy and it wasn’t until later that they really grew close.

“He was always so gracious, and we would talk about the old times, and never did he act like, 'Oh, I knew you guys were scared because I was so good.' It was just pleasure to know the guy,” Letterman said. “He was a gentleman and delightful.”

Williams was an often interview subject for Letterman, appearing on his show 50 times. ABC News reports that he also showed a highlight reel of great Williams jokes.

“Beyond being a very talented man and a good friend and a gentleman, I’m sorry like everybody else I had no idea that the man was in pain, that the man was suffering,” Letterman said. “But what a guy.”

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Jimmy Fallon, Seth Meyers and Conan O’Brien paid their respects last week.

Williams died last Monday at age 63 from suicide.

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