Musnad Ahmad 28:533

Abu Ahmad narrated to us, Yunus ibn al-Harith narrated to us, from Amr ibn Shu’ayb, from his father, from his grandfather, that the Messenger of Allah (may Allah bless him and grant him peace) only performed Qiran (combining Hajj and Umrah) for fear that he would be prevented from reaching the House. And he said: "If it is not a Hajj, then it is an Umrah."