What sutta refers to 'emptiness in small space'? I remember reading about one sutta  "emptiness in small gap". Since consciousness (Vijñāna) raises and falls all the time, between each consciousness there is a very small and briefest gap where Vijñāna doesn't take place. If i remember correctly, Buddha might have said about this emptiness as FYI. Anyone could help me find sutta about "emptiness in small gap" or "emptiness in small space", or "void in tight space".  i want to study this sutta again to see if buddha ralated this emptiness to vimutti or maha-sunyata.    thanks
I have never read a Sutta talking about emptiness in terms of a gap or a small space, and to my knowledge the Suttas don't explicitly talk about what happens between individual consciousnesses (although the commentaries on the Suttas do interpret certain passages as referring to it).

Within the Theravada Abhidhamma, this issue is taken up more explicitly. According to the Abhidhamma, between individual consciousnesses there is another type of mind-state called the Bhavanga-citta. The Ven. Bhikkhu Bodhi in his book A Comprehensive Manual of Abhidhamma explains the Bhavanga quite succinctly as follows on page 106:


  (2) Life-continuum (bhavanga):  The word bhavanga means “factor (anga)
  of  existence (bhava),” that is, “the indispensable condition of
  existence.”  Bhavanga is the  function of consciousness by which the
  continuity of the individual is preserved through  the duration of any
  single existence, from conception to death.  After the paṭisandhicitta
  has arisen and fallen away, it is then followed by the bhavangacitta,
  which is a resultant  consciousness  of  the  same  type  as  the 
  paṭisandhicitta  but  which  performs  a  different  function, 
  namely,  the  function  of  preserving  the  continuity  of 
  individual  existence.
  Bhavangacittas  arise  and  pass  away  every  moment  during  life  whenever  there  is  no  active cognitive process taking place.  This
  type of consciousness is most evident during deep dreamless sleep, but
  it also occurs momentarily during waking life countless times  between
  occasions of active cognition.  When an object impinges on a sense
  door, the bhavanga is arrested, and an active  cognitive process
  ensues for the purpose of cognizing the object.  Immediately after the
  cognitive process is completed, again the bhavanga supervenes and
  continues until the  next cognitive process arises.  Arising and
  perishing at every moment during this passive  phase of consciousness,
  the bhavanga flows on like a stream (sota), without remaining  static
  for two consecutive moments.


(Emphasis added)