Sahih Bukhari Volume 002, Book 026, Hadith Number 683.
Narated By 'Urwa : 'Aisha said, "The first thing the Prophet did on reaching Mecca, was the ablution and then he performed Tawaf of the Ka'ba and that was not 'Umra (alone), (but Hajj-al-Qiran). 'Urwa added: Later Abu Bakr and 'Umar did the same in their Hajj." And I performed the Hajj with my father Az-Zubair, and the first thing he did was Tawaf of the Ka'ba. Later I saw the Muhajirin (Emigrants) and the Ansar doing the same. My mother (Asma') told me that she, her sister ('Aisha), Az-Zubair and such and such persons assumed Ihram for 'Umra, and after they passed their hands over the Black Stone Corner (of the Ka'ba) they finished the Ihram. (i.e. After doing Tawaf of the Ka'ba and Sa'i between Safa-Marwa.