Sahih Bukhari Volume 003, Book 028, Hadith Number 040.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 28. Pilgrims Prevented from Completing the Pilgrimmage
Narated By Nafi : When Abdullah bin 'Umar set out for Mecca with the intentions performing 'Umra in the period of afflictions, he said, "If I should be prevented from reaching the Ka'ba, then I would do the same as we did while in the company of Allah's Apostle." So, he assumed the Ihram for 'Umra since the Prophet had assumed the Ihram for 'Umra in the year of Al-Hudaibiya. Then 'Abdullah bin 'Umar thought about it and said, "The conditions for both Hajj and 'Umra are similar." He then turned towards his companions and said, "The conditions of both Hajj and 'Umra are similar and I make you witnesses that I have made the performance of Hajj obligatory for myself along with 'Umra." He then performed one Tawaf (between As-Safa and Al-Marwa) for both of them (i.e. Hajj and ('Umra) and considered that to be sufficient for him and offered a Hadi.