Musnad Ahmad 790:137

Sulayman ibn Harb and Hasan ibn Musa narrated to us, they said: Hammad ibn Zayd narrated to us, Ghaylan ibn Jarir narrated to us, from Mutarrif, who said: I and Imran prayed behind Ali ibn Abi Talib. When he prostrated, he would say "Allahu Akbar" (takbir), and when he raised his head, he would say "Allahu Akbar," and when he rose from the two rak'ahs, he would say "Allahu Akbar." When we finished, Imran ibn al-Husayn took my hand and said: "This man has led us in prayer just like the prayer of Muhammad, may Allah bless him and grant him peace," or he said: "This man has reminded me of the prayer of Muhammad, may Allah bless him and grant him peace."