The Prophet ﷺ said: The greatest war, the conquest of Constantinople and the coming forth of the Dajjal (Antichrist) will take place within a period of seven months. (Using translation from Abū Dāʾūd 4295)
قَالَ رَسُولُ اللهِ ﷺ الْمَلْحَمَةُ الْعُظْمَى وَفَتْحُ الْقُسْطَنْطِينِيَّةِ وَخُرُوجُ الدَّجَّالِ فِي سَبْعَةِ أَشْهُرٍ