Daniel 12:1 explicitly speaks of a time of trouble unmatched in history — the direct source for Jesus' wording here.

Joel 2:2 describes a day of darkness and gloom, such as never was — directly parallels Jesus' 'such as has not been from the beginning'.

Mark 13:9 warns of persecution in councils — a different aspect of the same Olivet Discourse, focusing on personal trials.

Luke 21:24 parallels this discourse, adding that Jerusalem will be trampled until the times of the Gentiles are fulfilled.

Exodus 9:24 describes unprecedented hail and fire, showing a previous calamity that this tribulation surpasses.

2 Kings 21:12 prophesies such evil on Jerusalem that ears tingle, echoing the unprecedented nature.

Jeremiah 30:7 explicitly calls it a time of trouble like none other, the OT prophecy of this great tribulation.

Ezekiel 5:9 threatens a punishment never done before and never to be repeated — the exact same logic of unprecedented judgment Jesus uses here.

Daniel 9:12 states that no calamity like Jerusalem's exile had ever happened — directly paralleling Jesus' claim of unprecedented tribulation.

Mark 13:19 is the parallel account of this same prophecy, using almost identical wording about unprecedented tribulation from creation's beginning.