Sahih Bukhari Volume 2, Book 26, Hadith Number 686.

Narated By Um Salama : (The wife of the Prophet) I informed Allah’s Apostle that I was ill. So he said, “Perform the Tawaf while riding behind the people.” I did so, and at that time the Prophet was praying beside the Ka’ba and reciting Surat-at-Tur.