Musannaf Ibn Abi Shayba 3:4055

Yazid ibn Harun narrated to us, he said: Abu 'Amir al-Muzani, Salih ibn Rustum, informed us, from Ibn Abi Mulaykah, from Ibn 'Abbas, who said: The morning prayer was called, so a man stood up to pray the two rak'ahs. The Messenger of Allah, may Allah bless him and grant him peace, pulled his garment and said: "Are you praying the morning [prayer] as four?"