WATCH: David Letterman’s touching tribute to long-time friend Robin Williams

On Monday night’s “Late Show,” David Letterman paid tribute to Robin Williams, who died last week while the late night program was in reruns.

The host dedicated a 10-minute segment to Williams, recalling their earliest interactions at The Comedy Store in Los Angeles when both stand-up comedians were just starting their careers. Letterman noted that Williams’ performance was like “nothing we’d ever seen before… we’re like morning dew, he comes in like a hurricane. The longer he was on stage, the worse we feel about ourselves, because it’s not stopping. And then he finishes, and I thought, ‘oh, that’s it, they’re gonna have to put an end to showbusiness, because what can happen after this?'”

As well as reminiscing about his disastrous guest appearance on Williams’ “Mork and Mindy,” Letterman ran a clip package of some of the star’s appearances on his show, before ending on a subdued note.

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