New York (CBS Entertainment) – David Letterman used his opening monologue on the “Late Show” Monday to remember old pal Robin Williams.

In his first day since news broke of the passing of Robin Williams, Letterman shared personal memories of his early years working the Los Angeles comedy club circuit alongside a then-up-and-coming Williams. 

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Williams, 63, committed suicide last week inside his California home.

“I knew Robin for 38 years — 38 years. Which in and of itself is crazy how time…,” Letterman said before trailing off for a moment during the 10-minute tribute, which he delivered from behind his desk.

“He and I were kids…we wanted to make people laugh…In those days we were working for free drinks… It wasn’t until I started the NBC version of this show… it wasn’t until then that I sort of got to really know Robin Williams. He would come on to promote movies, or concerts, or whatever he was talking about, and he was always so gracious and we would talk about the old times. It was just a pleasure to know the guy. He was a gentleman and delightful,” Letterman said.

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Williams’ wife, Susan Schneider, revealed that the Oscar-winner had been diagnosed with Parkinson’s disease

“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 in his closing words, “What a guy, Robin Williams.”

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