It is narrated from Sayyiduna Abu Tha'labah (may Allah be pleased with him) (sometimes the narrator Mu'awiyah reported it as the Prophet's own words and sometimes he did not) that the Messenger of Allah (peace and blessings be upon him) said: "Allah will not leave this Ummah unable to last half a day; and when you see Sham as the dining spread of one man and his household, then at that time Constantinople will be conquered."
Hadith Referenceالمعجم الكبير للطبراني / باب اللام ألف / 18792