The only relevant source in Russian I could find - the book of a modern writer, Albert Tussein, on proza.ru
http://proza.ru/2014/07/05/656

Except for that Google doesn't know about other books with this quote or variations of it. Search for "most beautiful", "not guilty" etc. in combination with Gorky's name brings nothing.

So either Gorky never said something like this and Tussein misattributed the quote, Google (and Duckduckgo) do not index the source or the source isn't digitized.