I am searching for a Twain quote, but cannot find it.

It goes something like:
It is best to keep silent and be thought a fool than to open one's mouth
and remove all doubt.

Since every quote that sounds 'Twainian' is attributed to Mark Twain, is
this indeed his? If not, whose?

If it is Twain's, a source would help.

(I need to buy the recent book that is supposed to be the ultimate
reference on Twain quotes.  Can anyone tell me the title and author?  I
wrote it down a few months ago, but I am organizationally impaired.)

Prompt responses will be appreciated.

Thank you,
C.J. Peiffer