'Great Tribulation' in the Bible

And I applied my heart to seek and to search out by wisdom concerning all that is done under heaven. It is a great tribulation that God has given to the sons of men to be exercised therewith.

In the third year of Cyrus king of Persia a message was revealed to Daniel, who was named Belteshazzar; and the message was true and it referred to great conflict (warfare, misery). And he understood the message and had an understanding of the vision.

For then shall be great tribulation, such as was not since the beginning of the world to this time, no, nor ever shall be.

'And there came a dearth upon all the land of Egypt and Canaan, and great tribulation, and our fathers were not finding sustenance,

Behold, I will cast her into a bed, and them that commit adultery with her into great tribulation, except they repent of their deeds.

And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb.