Abu al-Aliyah al-Riyahi narrates: Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) was in a quarter of Isfahan, and the people there did not have much fear at that time, but he wanted to teach them their religion and the Sunnah of their Prophet. So he arranged them in two rows: one group stood with him, carrying weapons and facing the enemy, and another group was behind it. He led those near him in one rak'ah; then they stepped back on their heels until they stood in the place of the others, passing between them, and the others stood behind him. Then Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) led the others in one rak'ah, and then he concluded with the salam. Then those who had been behind him stood up, and the others stood up too, and each prayed one rak'ah; then they concluded with the salam one after another. Thus the imam had two rak'ahs and the people one rak'ah each.
Al-Tabarani recorded it in al-Mu'jam al-Kabir and al-Mu'jam al-Awsat in similar wording; the narrators of al-Mu'jam al-Kabir are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 3198