I am looking for quotation by Thomas Jefferson that states that “Jury
service may be more important than voting in a democracy”, do not know
if this quotation is correct in its current form.  However, the
general gist of the phrase should be correct. Am interested in
receiving the source of this quotation for reference proposes so I may
site the document or speech that Thomas Jefferson is quoted in.

Hello.

I am confident that this is the quotation that you want:

"Were I called upon to decide whether the people had best be omitted
in the Legislative or Judiciary department, I would say it is better
to leave them out of the Legislative. The execution of the laws is
more important than the making of them."
(Letter to the Abbé Arnoux, 1789; The Papers of Thomas Jefferson, Vol.
15, p. 283, Princeton University Press, 1958)
http://www.wsba.org/media/publications/barnews/archives/1999/jul-99-letters.htm

The quotation clearly has the exact meaning that you want. Jefferson
is saying that it is more important to have the people participating
in the judicial branch (i.e., as jurors) than in the legislative
branch (i.e., as voters).

------------------

Additional sources:

'Thomas Jefferson said "I consider trial by jury the only anchor yet
imagined by man, by which a government can be held to the principles
of it's constitution." If you think that Jefferson overlooked the
right to elect our representatives, you should consider a second quote
of Jefferson, from a letter written in 1789, while serving. as
ambassador to France: "Were I called upon to decide whether the people
had best be omitted in the Legislative or Judiciary department, I
would say that it is better to leave them out of the Legislative."'
source:
Does The Right To Sit on a Jury Give you as much Political Power as
the Right to Vote in Elections? Author: Jack Stewart
http://www.geocities.com/stewjackmail/pdf/jury.pdf

"PRACTICE AND POTENTIAL OF THE ADVISORY JURY.
...
Were I called upon to decide whether the people had best be omitted in
the Legislative or Judiciary department, I would say it is better to
leave them out of the Legislature. The execution of the laws is more
important than the making [of] them.-- Thomas Jefferson
Harvard Law Review APRIL, 1987 100 Harv. L. Rev.1363
http://freedomlaw.com/advis.htm

search strategy:
"thomas jefferson", jury, quote
"thomas jefferson", jury, "the people"
"thomas jefferson", jury, "people has best be omitted"

I hope this helps.