Jason Alexander is wishing his former “Seinfeld” co-star and friend Jerry Seinfeld “serenity now” as the comedian launches a book of comedy — his first in 25 years — Is This Anything?.

Seinfeld was on “Good Morning America” when host co-host George Stephanopoulos surprised him with a video greeting from Alexander.

“Apparently my old pal Jerry Seinfeld has written a new book. Well, that’s not surprising — Jerry’s written every book you see on the shelves behind me,” he says gesturing to his library. “This is just the Seinfeld section,” he says as Seinfeld laughs.

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“Congratulations, Jer. I’m sure it’s gonna be another huge success. I love you brother and as we used to say on Stage 9, ‘Serenity now,'” he adds.

Seinfeld has saved every bit of comedy he’s ever written on large yellow legal pads and has now compiled decades of his notes to form his new book.

“Whenever I came up with a funny bit, whether it happened on stage, in a conversation, or working it out on my preferred canvas, the big yellow legal pad, I kept it in one of those old-school accordion folders,” Seinfeld says in a press release. “I have every piece of standup comedy I thought was worth saving from 45 years of hacking away at this for all I was worth.”

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Seinfeld tells “GMA” the 400-plus-page book took a year to assemble, explaining he saved all his jokes over the years because “to me, [this] has great value.”

“Why would I save anything else?” he asks. “A lot of them were just notes or scratching, so I had to really assemble the whole thing.”

Is This Anything? is released on Oct. 6.

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