Jubayr bin Nufayr al-Hadrami · Battles (Kitab Al-Malahim)

I heard the Messenger of Allah (ﷺ) say: you will make a secure peace with the Byzantines, then you and they will fight an enemy behind you, and you will be victorious, take booty, and be safe. You will then return and alight in a meadow with mounds and one of the Christians will raise the cross and say: The cross has conquered. One of the Muslims will become angry and smash it, and the Byzantines will act treacherously and…

The Prophet (ﷺ) said: The time between the great war and the conquest of the city (Constantinople) will be six years, and the Dajjal (Antichrist) will come forth in the seventh. Abu Dawud said: This is sounder than the tradition narrated by Isa (bin Yunus)