Musannaf Ibn Abi Shayba 3:114

Abu Bakr ibn Ayyash narrated to us, from Abu Ishaq, from Yazid ibn Abi Maryam, from Abu Musa, who said: Ali led us in prayer on the day of the Camel, a prayer by which he reminded us of the prayer of the Messenger of Allah (may Allah bless him and grant him peace). Either we had forgotten it, or we had abandoned it intentionally: he would say the takbir in every lowering and rising, and in every standing and sitting, and he would say the taslim to his right and to his left.