Musannaf Ibn Abi Shayba 3:3441

Humaid ibn Abd al-Rahman narrated to us, from Hasan, from Ibn Abi Layla, that Ali ordered a man to lead the people in prayer in the Mosque of Kufa for two rak'ahs. He said: And Ibn Abi Layla said: He prays two rak'ahs. A man said to Ibn Abi Layla: "Does he pray without a khutbah (sermon)?" He said: "Yes."