Four thousand two hundred and ninety-one years after the creation of the world the wars of the dragons and the wars of Gog and Magog will cease, and the rest of the time will be the days of the Messiah; and the Holy One — blessed be He! — will not renew His world till after seven thousand years.... Rabbi Jonathan said, " May the bones of those who compute the latter days (when the Messiah shall appear) be blown; for some say, ( Because the time (of Messiah) has come and Himself has not, therefore He will never come! ' But wait thou for Him, as it is said (Hab. ii. 3), ( Though He tarry, wait for Him.* Perhaps you will say, ( We wait, but He does not wait; ' learn rather to say (Isa. xxx. 18), (And therefore will the Lord wait, that He may be gracious unto you; and therefore will He be exalted, that
Cursing the Bones of the Messiah-Calculators
Sanhedrin 97b