The Prophet ﷺ said: The place of assembly of the Muslims at the time of the war will be in al-Ghutah near a city called Damascus, one of the best cities in Syria.  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِنَّ فُسْطَاطَ الْمُسْلِمِينَ يَوْمَ الْمَلْحَمَةِ بِالْغُوطَةِ إِلَى جَانِبِ مَدِينَةٍ يُقَالُ لَهَا دِمَشْقُ مِنْ خَيْرِ مَدَائِنِ الشَّامِ  

Ibn ‘Umar reported the Messenger of Allah (May peace be upon him)As saying: The Muslims will soon be besieged up to Madina so that their most distant frontier outpost will be Salah.  

قَالَ رَسُولُ اللَّهِ ﷺ يُوشِكُ الْمُسْلِمُونَ أَنْ يُحَاصَرُوا إِلَى الْمَدِينَةِ حَتَّى يَكُونَ أَبْعَدَ مَسَالِحِهِمْ سَلاَحُ  

Salah is near Khaibar.  

وَسَلاَحُ قَرِيبٌ مِنْ خَيْبَرَ