The question addressed here is, Where does one find the seven year Tribulation in the Bible? The answer is, It comes from Daniel's prophecy of the seventy weeks in Daniel 9:24-27. There, in that passage, addressing both the first and second comings of the Messiah, an angel told Daniel:
Seventy weeks  are determined for your people and for your holy city, to finish the transgression, to make an end of sins, to make reconciliation for iniquity, to bring in everlasting righteousness, to seal up vision and prophesy, and to anoint the Most Holy. Know therefore and understand, that from the going forth of the command to restore and build Jerusalem [fulfilled by Artaxerxes in 445 BC. See Nehemiah 2:5-8) until Messiah the Prince, there shall be seven weeks and sixty-two weeks ; the street shall be built again, and the wall [accomplished under Nehemiah], even in troublesome times. And after the sixty-two weeks, Messiah shall be cut off, [speaking of the cross] but not for himself [speaking of his death for you and me]; and the people [the Romans] of the prince who is to come [Antichrist] shall destroy the city and the sanctuary [destroyed by the Roman general, Titus, in AD 70]. The end of it shall be with a flood, and till the end of the war desolations are determined. Then he [Antichrist] shall confirm a covenant [make a treaty] with many for one week; [a seven year treaty with the Jews initiated at the beginning of the Tribulation] but in the middle [3 1/2 years after the treaty, at the beginning of the Great Tribulation] of the week he shall bring an end to sacrifice and offering. And on the wing of abominations shall be one who makes desolate, [Antichrist’s cutting off of the temple’s operations and setting up his own worship there] even until the consummation, which is determined, is poured out on the desolate [Christ's judgment of Antichrist at the Second Coming, casting him into the Lake of Fire].
As far as exact dates and times are
concerned, this is the most amazingly precise prophecy in the entire Bible.
Three key portions of it have already been fulfilled, namely:
…the issuing of the decree to restore and build Jerusalem.
…the precise date of the coming of Messiah.
…the cutting off of Messiah at the cross.
When Sir Robert Anderson calculated the
time between Artaxerxes decree (445 BC) to the first coming of Christ the
Messiah, he found that it was exactly 483 years, just as Daniel had predicted
when he wrote, from the going forth of the command to
restore and build Jerusalem until Messiah the Prince, there shall be seven weeks
and sixty-two weeks (69 weeks). Using simple mathematics, Sir
Robert Anderson found that Daniel's seventy weeks
referred to time periods of seven years each or “prophetic weeks.” So, 69
prophetic weeks equaled 7 X 69 = 483 years. He then calculated that from
Artaxerxes' decree, in the days of Nehemiah, to the day when Jesus rode into
Jerusalem on a donkey's colt and presented himself to Israel as their Messiah,
was exactly 483 years. In fact, this turned out to be so precise a prediction
that liberal theologians immediately began to say that the book of Daniel was
not written by Daniel at all, but must have been written by someone else at a
much later time! Careful study of Daniel, however, proves otherwise. The
historicity and date of Daniel's writings are beyond question. This is dealt
with extensively by Sir Robert Anderson in his classic book, The Coming
Prince. The following is a quote from that book citing Sir
Robert Anderson's calculations (Anderson, Pickering and Inglis, Ltd., London,
13th Edition, n.d. pp. 127 - 128),
In accordance with the Jewish custom, the Lord went up to Jerusalem upon the 8th of Nisan, 'six days before the passover.' But as the 14th, on which the Paschal Supper was eaten, fell that year on a Thursday, the 8th was the preceding Friday. He must have spent the Sabbath, therefore, at Bethany; and on the evening of the 9th, after the Sabbath had ended, the Supper took place in Martha's house. Upon the following day, the 10th of Nisan, He entered Jerusalem as recorded in the Gospels. The Triumphal entry, the end of the 69 sevens cf. Zech. 9:9. The Julian date of that 10th of Nisan was Sunday the 6th of April, a.d. 32. What then was the length of the period intervening between the issuing of the decree to rebuild Jerusalem and the public advent of 'Messiah the Prince,' -- between the 14th March b.c. 445, and the 6th April, a.d. 32? THE INTERVAL CONTAINED EXACTLY, AND TO THE VERY DAY, 173,880 DAYS, OR SEVEN TIMES SIXTY-NINE PROPHETIC YEARS OF 360 DAYS, the first sixty-nine weeks of Gabriel's prophecy.
The 1st Nisan in the 20th year of Artaxerxes (the edict to rebuild Jerusalem) was 14th March, b.c. 445.
The 10th Nisan in Passion Week (Christ's entry into Jerusalem) was 6th April, a.d. 32.
The intervening period was 476 years and 24 days (the days being reckoned inclusively, as required by the language of the prophecy, and in accordance with the Jewish practice.)
But 476 x 365 = 173,740 days
Add (14th March to 6th April, both inclusive) 24 "
Add for leap years 116 "
Add 69 weeks of prophetic years of 360 days (or 69 x 7 x 360) = 173,880 days.
Coming back to Daniel's prophecy, this means that there now remains only one week (7 years) that has not yet been fulfilled. When Messiah was cut off at the cross, Daniel's prophetic 70 week prophetic clock stopped, leaving its final week yet unfulfilled. It will be fulfilled by the Tribulation. In the Old Testament, the mystery of the Church and its time period (from the cross of Christ until now), is not found. The Church was not revealed in the Old Testament, you see. So, the mystery of the Church Age lies between Daniel's 69th and 70th week. When the Rapture of the Church occurs, it will bring the Church Age to a close and kick off the beginning of Daniel's 70th week. Daniel's seventy weeks will then resume ... and begin to tick down, once again, allowing its final week to be fulfilled by seven years of Earth's secular history. When those days have run their course, then ... all of Daniel's prophecy will have been fulfilled.
Other references to the 7 year Tribulation come from the scriptures that mention its two 3 � year segments. The last 3 � years is called The Great Tribulation. Here are those scriptures. You can draw your own conclusions about them:
1. Revelation 11:3, says that God's two witnesses will prophesy at Jerusalem for one thousand two hundred and sixty days (1260 divided by 360 = 3 1/2 years).
2. Revelation 12:6, says that the woman, Israel, will be hidden in the wilderness for one thousand two hundred and sixty days (1260 divided by 360 = 3 1/2 years).
3. Revelation 13:5, says that the beast with the big mouth (Antichrist) was granted to continue for forty-two months (42 divided by 12 = 3 1/2 years).
4. Daniel 7:25, says that the saints will be given into the hands of the little horn (Antichrist) for a time and times and half a time (a Jewish idiomatic expression where the term time means one year) (1 + 2 + 1/2 = 3 1/2 years).
5. Daniel 12:11, says that from the time that the sacrifice is caused to cease and the abomination of desolation is set up (until the end) will be one thousand two hundred and ninety days (1290 divided by 360 = 3 1/2 years + an extra 30 days). We don't know what that extra 30 days is all about. It is still a mystery.
6. Daniel 12:12, says that there will be one thousand three hundred and thirty five days until the day when all who arrive in Israel will be called blessed (1335 divided by 360 = 3 1/2 years + an extra 75 days). Apparently, this refers to a particular “red-letter” day that will take place at the beginning of the Millennial Kingdom of Christ … calculated from the day that the sacrifice was stopped by Antichrist at the middle of the Tribulation.
So, Daniel 9:24-27, is the prophecy that lays the foundation for the 7 year Tribulation Period. Several of its predictions and time periods have already been fulfilled with such preciseness and precision that the predictions of the entire prophecy is, in my opinion, beyond question. There is only one piece that is yet to be fulfilled, namely its last 7 year period or final week.
In addition, there are the other scriptures quoted above that predict the 3 1/2 year segments of the Tribulation that are yet to be fulfilled in history. These fit perfectly with Daniel’s 70th week. Together, these scriptures clearly predict that the length of the Tribulation will be seven years.
Scripture taken from the New King James Version. Copyright 1982 by Thomas Nelson, Inc. Used by permission. All rights reserved.