Musnad Abu Ya'la al-Mawsili 45:3

Abu Bakr narrated to us, Abu Khalid al-Ahmar and Abu Mu'awiyah narrated to us, from Hajjaj, from al-Hasan ibn Sa'd, from Ibn Abbas, who said: Abu Talha informed me that the Messenger of Allah (may Allah bless him and grant him peace) combined the Hajj and the Umrah.