For the nation of Israel this will be the worst time in it's entire history. The Antichrist (counterfeit Messiah) will be the Jews' worst persecutor as he attempts to thwart the fulfillment of God's pledge of salvation and a kingdom for Israel. After posing as their protector for the first half of the Tribulation Period, he will Break His Covenant with them (Dan. 9:27). He will then unleash a persecution unparalleled in history.(1)
This persecution is believed by many to be linked to Zechariah 13:8 which many scholars believe will be Israel's final end-time battle between Gog of Magog and Israel. This battle may eradicate 2 of every 3 Jews living in Israel and will end only with the return of their Messiah.
The prophet Jeremiah compares the increasing tribulation and distress that Israel will go through to labor pains of a mother about to give birth.
Jeremiah 30 5-7 "This is what the LORD says: "'Cries of fear are heard-- terror, not peace. Ask and see: Can a man bear children? Then why do I see every strong man with his hands on his stomach like a woman in labor, every face turned deathly pale? How awful that day will be! None will be like it. It will be a time of trouble for Jacob, but he will be saved out of it.
In the New Testament Jesus draws upon this passage while providing further revelation.
Matthew 24:6-8 You will hear of wars and rumors of wars, but see to it that you are not alarmed. Such things must happen, but the end is still to come. Nation will rise against nation, and kingdom against kingdom. There will be famines and earthquakes in various places. All these are the beginning of birth pains.
The prophet Daniel also was given a vision concerning this event.
Daniel 12:1 "Now at that time Michael, the great prince who stands guard over the sons of your people, will arise. And there will be a time of distress such as never occurred since there was a nation until that time; and at that time your people, everyone who is found written in the book, will be rescued.
The prophet Zephaniah describes the tribulation this way.
Zephaniah 1:15 That day will be a day of wrath, a day of distress and anguish, a day of trouble and ruin, a day of darkness and gloom, a day of clouds and blackness...
The day of the Lordis a term that refers to a period of time, not necessarily just one calendar day. Sometimes when used by a prophet it refers to an event that is soon to occur (the near view). Other times the term is used when talking about future prophetic end-time events that have not happened yet (the far view). It usually involves Israel in some way, often involving judgment. When used for the the far view purpose, the day of the Lord in the Old Testament is often the same as John's prophetic visions in the New Testament (Book of Revelation).When this happens, it is the time of the coming of the Messiah in judgment.(2)
More on the Day Of The Lord.
The Ending Of Jacob's Trouble:
Moses knew about this time and He knew that Israel would indeed be delivered from this wrath in the end. Moses wrote "When you are in distress and all these things have come upon you, in the latter days you will return to the Lord your God and listen to His voice" (Deut. 4:30).
That's also what Zechariah talked about when he wrote “I will pour out on the house of David and on the inhabitants of Jerusalem, the Spirit of grace and of supplication, so that they will look on Me whom they have pierced; and they will mourn for Him, as one mourns for an only son, and they will weep bitterly over Him like the bitter weeping over a firstborn (Zech. 12:10).
Both these prophets saw Israel's repentance and God's grace for Israel.
There is a passage in the talmud that may refer to the struggles that Israel will experience just before Messiah's return. For more on this please see Israel Will Repent.
Pages inside JewishRoots.Net that are tribulation related include:
Going through this period of Jacob's trouble will prepare Israel for the Millennial Kingdom and bring the prophecy of Dan 9:24-27 to an end.
1). The MacArthur New Testament Commentary on 1&2 Thessalonians p.265
2). The Popular Encyclopedia of Bible Prophecy by Tim Lahaye.