Musnad Ahmad 27:1780

Ishaq ibn Yusuf narrated to us, from Sharik, from Abdullah ibn Sharik al-Amiri, who said: I heard Abdullah ibn Umar, Abdullah ibn Abbas, and Abdullah ibn al-Zubayr being asked about the Umrah before the Hajj in the Mut'ah. They said: "Yes, it is the Sunnah of the Messenger of Allah, peace and blessings of Allah be upon him. You perform it first, then you circumambulate the House (the Kaaba) and go between al-Safa and al-Marwah, then you exit the state of Ihram, even if that is one day before the Day of Arafah. Then you enter the state of Ihram for Hajj. Thus, you have combined an Umrah and a Hajj, or Allah has combined for you an Umrah and a Hajj."