Musnad Ahmad 790:26

Muhammad ibn Ja‘far narrated to us, Sa‘id narrated to us, from Ghaylan ibn Jarir, and ‘Abd al-Wahhab, from a companion of his, from Ghaylan ibn Jarir, from Mutarrif ibn al-Shikhkhir, that he said: I was with ‘Imran ibn Husayn in Kufa, and ‘Ali ibn Abi Talib led us in prayer. He would say the takbir whenever he prostrated and whenever he raised his head. When he finished, ‘Imran said: "This man led us in a prayer like the prayer of the Messenger of Allah, may Allah bless him and grant him peace."