The Talmud (Sanhedrin 97a-b):
"The world will continue for six thousand years, the first two thousand of which were a chaos (Tahu), the second two thousand were of Torah, and the third two thousand are the days of the Messiah, and because of our sins many years of these have elapsed, and still he has not come."
--Rodkinson, Michael L. (2009-06-01). The Babylonian Talmud, all 20 volumes (mobi) (Kindle Locations 61483-61486). MobileReference. Kindle Edition.