"Mystics" in buddhism? ("There is nothing hidden in my teaching" and the like) 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 occurrence 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"...
It's the Mahaparinibbana Sutta, DN 16:

31. And the Blessed One recovered from that illness; and soon after his recovery he came out from his dwelling place and sat down in the shade of the building, on a seat prepared for him. Then the Venerable Ananda approached the Blessed One, respectfully greeted him, and sitting down at one side, he spoke to the Blessed One, saying: &quot;Fortunate it is for me, O Lord, to see the Blessed One at ease again! Fortunate it is for me, O Lord, to see the Blessed One recovered! For truly, Lord, when I saw the Blessed One's sickness it was as though my own body became weak as a creeper, every thing around became dim to me, and my senses failed me. Yet, Lord, I still had some little comfort in the thought that the Blessed One would not come to his final passing away until he had given some last instructions respecting the community of bhikkhus.&quot;
32. Thus spoke the Venerable Ananda, but the Blessed One answered him, saying: &quot;What more does the community of bhikkhus expect from me, Ananda? I have set forth the Dhamma without making any distinction of esoteric and exoteric doctrine; there is nothing, Ananda, with regard to the teachings that the Tathagata holds to the last with the closed fist of a teacher who keeps some things back. Whosoever may think that it is he who should lead the community of bhikkhus, or that the community depends upon him, it is such a one that would have to give last instructions respecting them. But, Ananda, the Tathagata has no such idea as that it is he who should lead the community of bhikkhus, or that the community depends upon him. So what instructions should he have to give respecting the community of bhikkhus?
(source)

The Pali is simply:

natthānanda tathāgatassa dhammesu ācariyamuṭṭhi.
Ananda, there is no teacher's fist in regards to the dhammas of the Tathāgata.