The Prophet ﷺ said, "Have you heard of a city, one side of which is on land and the other side in the sea?"They replied, "Yes, Messenger of Allah."He said, "The Hour will not come until seventy thousand from the descendants of Ishaq attack it. When they reach it, they will encamp there. They will not fight with weapons, nor will they shoot a single arrow. They will say, 'There is no god but Allah, and Allah is the greatest,' and one of its two sides will fall."Thawr said, I only know him to have said, "The side that is in the sea. Then they will say a second time, 'There is no god but Allah, and Allah is the greatest,' and its other side will fall. Then they will say a third time, 'There is no god but Allah, and Allah is the greatest,' and it will be opened to them. They will enter it and take its spoils. While they are dividing the spoils, a crier will come to them and announce that the Dajjal has appeared, so they will leave everything and return."
أن النبي ﷺ قال: سمعتم بمدينة جانب منها في البر، وجانب منها في البحر؟ قالوا: نعم، يا رسول الله، قال: لا تقوم الساعة حتى يغزوها سبعون ألفا من بني إسحاق، فإذا جاؤوها نزلوا، فلم يقاتلوا بسلاح، ولم يرموا بسهم، قالوا: لا إله إلا الله والله أكبر، فيسقط أحد جانبيها. قال ثور: لا أعلمه إلا قال: الذي في البحر، ثم يقولوا الثانية: لا إله إلا الله والله أكبر، فيسقط جانبها الآخر، ثم يقولوا الثالثة: لا إله إلا الله والله أكبر، فيفرج لهم، فيدخلوها فيغنموا، فبينما هم يقتسمون المغانم، إذ جاءهم الصريخ، فقال: إن الدجال قد خرج، فيتركون كل شيء ويرجعون.
Muslim narrated it in the Book of Tribulations and the Signs of the Hour (2920) from Qutayba bin Saeed, who said, Abdul-Aziz, meaning Ibn Muhammad, narrated to us, from Thawr, who is Ibn Zayd Dili, from Abu Ghayth, from Abu Hurairah, and he related it.Tirmidhi also narrated (2239), with a sahih chain of transmission, from Anas, who said, The conquest of Constantinople will coincide with the establishment of the Hour.