From Sahih Muslim (Hadith 2991):
Nafi' reported that Ibn Umar intended to go to Hajj (during the year) when Hajjaj attacked Ibn Zubair, and he narrated the account as (narrated above), and he used to say at the end of the hadith:He who combines Hajj with Umra, for him one single circumambulation is sufficient, and he did not put off Ihram until he had completed both of them
Reference: Muslim 2991