Musnad Ahmad 5:692

Abu Nu'aym narrated to us, Sufyan narrated to us, from al-Qasim ibn Kathir Abu Hashim, the seller of Sabiri (garments), from Qays al-Kharifi, who said: I heard Ali saying upon this pulpit: "The Messenger of Allah, may Allah bless him and grant him peace, preceded, and Abu Bakr prayed, and Umar made it three. Then a tribulation struck us—or a tribulation befell us—and then what Allah willed happened."