صحيح مسلم

Abu Huraira reported Allah's Messenger (may peace he upon him) saying: You have heard about a city, one side of which is on land and the other is in the sea (Constantinople). They said: Allah's Messenger, yes. Thereupon he said: The Last Hour would not come unless seventy thousand persons from Bani lshaq would attack it. When they would land there, they will neither fight with weapons nor would shower arrows but would only say: "There is no god but Allah and Allah is the Greatest," and one side of it would fall. Thaur (one of the narrators) said: I think that he said: The part by the side of the ocean. Then they would say for the second time: "There is no god but Allah and Allah is the Greatest" and the second side would also fall, and they would say: "There is no god but Allah and Allah is the Greatest," and the gates would be opened for them and they would enter therein and, they would be collecting spoils of war and distributing them amongst themselves when a noise would be heard saying: Verily, Dajjal has come. And thus they would leave everything there and go back.