It is narrated that Sayyiduna Amr bin Awf bin Milhah al-Muzani (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "The world will not end until there is a garrison of the Muslims (stationed) at Bawlan. O Ali!" (He (peace and blessings be upon him) meant Sayyiduna Ali bin Abi Talib (may Allah be pleased with him).) He said: Here I am, O Messenger of Allah. He (peace and blessings be upon him) said: "You will soon fight the Banu al-Asfar (the Romans), and the believers who come after you will also fight them. Then the choicest Muslims, the people of the Hijaz, will go out against them, striving in the path of Allah, not caring for the blame of any blamer in the matter of Allah, until Allah conquers Constantinople and Rumiyyah for them through tasbih and takbir. Allah will bring down its fortress, and they will obtain wealth so great that they never obtained the like of it before, so much so that they will divide (the wealth) by the measure of shields. Then a caller will cry out: O people of Islam, the Masih al-Dajjal has emerged in your lands! So the people will hold back from the wealth: some will take and some will leave, and the one who takes will be regretful and the one who leaves will be regretful. Then they will say: Who is this caller? And they will not know who he is. So they will say: Send a vanguard to Lud; if the Masih (al-Dajjal) has emerged, it will come to you with news of him. So they will go and look but will see nothing, and they will find the people silent. Then they will say: The caller called out only to us, so make a firm resolve, then decide rightly: we will all go out together to Lud; if the Masih al-Dajjal is there, we will fight him until Allah judges between us and him, and He is the best of judges; and if it is otherwise, then these are your own lands, your own clans and your own armies, and you will return to them."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14081