Musnad Ahmad 5:495

Abdullah narrated to us, Abu Bakr ibn Abi Shaybah narrated to us, Ibn Numayr narrated to us, from Abd al-Malik ibn Sulaym, from Abd Khayr, who said: I heard Ali saying: "Allah took His Prophet, may Allah bless him and grant him peace, upon the best state that any of the prophets, peace be upon them, were taken upon. Then Abu Bakr succeeded him, and he acted according to the practice of the Messenger of Allah, may Allah bless him and grant him peace, and the Sunnah of his Prophet, and Umar was likewise."