The Prophet ﷺ said: The building of the Holy Sanctuary (al-Aqsa) will be when Yathrib is in ruins, the ruined state of Yathrib will be when the great war comes, the outbreak of the great war will be at the conquest of Constantinople and the conquest of Constantinople when the Dajjal (Antichrist) comes forth. He (the Prophet) struck his thigh or his shoulder with his hand and said: This is as true as you are here or as you are sitting (meaning Mu'adh ibn Jabal).  

قَالَ رَسُولُ اللَّهِ ﷺ عُمْرَانُ بَيْتِ الْمَقْدِسِ خَرَابُ يَثْرِبَ وَخَرَابُ يَثْرِبَ خُرُوجُ الْمَلْحَمَةِ وَخُرُوجُ الْمَلْحَمَةِ فَتْحُ قُسْطَنْطِينِيَّةَ وَفَتْحُ الْقُسْطَنْطِينِيَّةِ خُرُوجُ الدَّجَّالِ ثُمَّ ضَرَبَ بِيَدِهِ عَلَى فَخِذِ الَّذِي حَدَّثَ أَوْ مَنْكِبِهِ ثُمَّ قَالَ إِنَّ هَذَا لَحَقٌّ كَمَا أَنَّكَ هَا هُنَا أَوْ كَمَا أَنَّكَ قَاعِدٌ يَعْنِي مُعَاذَ بْنَ جَبَلٍ