For our next meeting in the "interreligious dialogue" we members are asked to do a statement about the "mystics" in each ones religion.
Now, "mystics" is itself a mysterious term, I looked via wikipedia at some sources, what exactly the term means - well, not much more than that there is something hidden that noone else can see/sense/know, derived from the greek root of the term saying "closing eyes, closing the mouth". (Which does not mean that the term was not used for many speculative or intimate concepts in many religious threads, be it in Brahmanism (later, around the Buddha's time with the Upanishads and even later many that threads which we subsume now under "Hinduism"), Judaism ("Kabbala"), even Christianism (especially in the medieval east-european religious scene), Gnosticism and also Islam (by "Sufism") and surely other religious stands which I cannot name all here, and that it does not have a very broad usage over the cultures.)
For me, Buddhism (as I know it from the Tipitaka) has never been a matter with (systematically) "hidden" things/concepts (at least not prominently), so I tend to develop my statement towards something like "mysticism (in this sense) has not been intended by the Buddha" - and I remember vaguely that there is a sutta, where he explicitely says, there is no "closed fist" in my teaching or something very similar.
(Of course, meditating towards the occurence of Jhanas, the Jataka-stories, the Deva-worlds, the sutta about the Kalpas and the non-accesible "Beginning-of-all" deals with concepts which cannot be seen and need closed eyes, closed mouth and might be used as source for extended mysticism in folklore (I just recall the funny story of Maha-Mogallana, when he saw an otherwise invisible skeleton flying around and how this bizarre event made its way even into a discourse with the Buddha ...), but for me these are not so prominent as the teachings and guides for the analytic access to the relevant world)
So, my question is : in which sutta did the Buddha speak (explicitely/citeable (!) ) about that his teaching has nothing closed/hidden in it (as I think to recall with the term "fist")?
Addendum: I've put so much context around my question because it might as well be that there are (again explicitely/citeable) sayings which contrast this in a sensical way - of course when we meditate also we "close the eyes to look inside" and focus on the "inner world"...