Musnad Ahmad 28:147

Hassan narrated to us, Khalaf—meaning Ibn Khalifah—narrated to us, from Abu Janab, from his father, from Abdullah ibn Amr, who said: I entered upon the Prophet, peace and blessings of Allah be upon him, while he was performing ablution in a leisurely manner. He raised his head and looked at me, then said: "There are six [things] among you, O nation: the death of your Prophet,"—peace and blessings of Allah be upon him—and it was as if my heart had been plucked from its place. The Messenger of Allah, peace and blessings of Allah be upon him, said: "One." He said: "And wealth will overflow among you, until a man is given ten thousand, yet he remains dissatisfied with it." The Messenger of Allah, peace and blessings of Allah be upon him, said: "Two." He said: "And a tribulation that will enter the house of every man among you." The Messenger of Allah, peace and blessings of Allah be upon him, said: "Three." He said: "And death like the plague of sheep." The Messenger of Allah, peace and blessings of Allah be upon him, said: "Four." [He said]: "And a truce that will be between you and the Children of Yellow (the Byzantines); they will gather against you for nine months, the duration of a woman’s pregnancy, then they will be more prone to treachery than you." The Messenger of Allah, peace and blessings of Allah be upon him, said: "Five." He said: "And the conquest of a city." The Messenger of Allah, peace and blessings of Allah be upon him, said: "Six." I said: "O Messenger of Allah, which city?" He said: "Constantinople."