Silsilat al-Ahadith al-Sahihah

Abu Qabeel says: We were with Sayyiduna Abdullah bin Amr bin Al-As (may Allah be pleased with him), and he was asked: Which city will be conquered first, Constantinople or Rome? Sayyiduna Abdullah called for a box, which had rings attached to it. He took out a book from it. Then he said: We were sitting around the Messenger of Allah (peace and blessings be upon him), writing, when suddenly he was asked: Which city will be conquered first, Constantinople or Rome? The Messenger of Allah (peace and blessings be upon him) said: "The city of Heraclius (i.e., Constantinople) will be conquered first."