If you cite (not reprint hughe parts) from a written work you don't need the authors permission, but a chat can't count as a written word, but more like a spoken word from person to person and not from an author to the audience.
To put that rough in another way: If you listen to someone in a pub of whom you know he's known by others as well, would you ask for his permission to record his speaking and publish that on the next day news?
Well, in a pub you can't make sure that others listen to what you say, but that doesn't imply that you agree on publishing what you said.
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Have a nice day
All decision is left to your taste