Elijah the prophet said to Rav Yehuda, brother of Rav Sala Ḥasida: The world will exist no fewer than eighty-five Jubilee cycles, or 4,250 years. And during the final Jubilee, the son of David will come. Rav Yehuda said to Elijah: Will the Messiah come during the beginning of the Jubilee or during its end? Elijah said to Rav Yehuda: I do not know. Rav Yehuda asked: Will this last Jubilee cycle end before the Messiah comes or will it not yet end before his coming? Elijah said to him: I do not know. Rav Ashi says: This is what Elijah said to him: Until that time do not anticipate his coming; from this point forward anticipate his coming. Elijah did not inform Rav Yehuda of the date of the coming of the Messiah.

-Sanhedrin.97b.2

On that day Messiah’s feet will stand on the Mount of Olives, which is in front of Jerusalem on the east; and the Mount of Olives will be split in its middle from east to west forming a very large valley. Half of the mountain will move toward the north, and the other half toward the south. And you will flee by the valley of My mountains, for the valley of the mountains will reach to Azel; yes, you will flee just as you fled from the earthquake in the days of Uzziah king of Judah. Then the LORD, my God, will come, and all the holy ones with Him!

-Zechariah 14:4–5

Therefore, since all the works of God were completed in six days, the world must continue in its present state through six ages, that is, six thousand years. For the great day of God is limited by a circle of a thousand years, as the prophet shows, who says In Your sight, O Lord, a thousand years are as one day. And as God labored during those six days in creating such great works, so His religion and truth must labor during these six thousand years, while wickedness prevails and bears rule. And again, since God, having finished His works, rested the seventh day and blessed it, at the end of the six thousandth year all wickedness must be abolished from the earth, and righteousness reign for a thousand years; and there must be tranquility and rest from the labors which the world now has long endured.

-Lactantius, Divine Institutes 7.14.3

For in as many days as this world was made, in so many thousand years shall it be concluded. And for this reason the Scripture says: Thus the heaven and the earth were finished, and all their adornment. And God brought to a conclusion upon the sixth day the works that He had made; and God rested upon the seventh day from all His works. This is an account of the things formerly created, as also it is a prophecy of what is to come. For the day of the Lord is as a thousand years; and in six days created things were completed: it is evident, therefore, that they will come to an end at the sixth thousand year.

-Irenaeus, Against Heresies 5.28.3