Sahih Bukhari Volume 3, Book 47, Hadith Number 761.

Narated By Az-Zuhari : Ubaidullah bin ‘Abdullah told me that ‘Aisha had said, “When the Prophet became sick and his condition became serious, he requested his wives to allow him to be treated in my house, and they allowed him. He came out leaning on two men while his feet were dragging on the ground. He was walking between Al-‘Abbas and another man.” ‘Ubaidullah said, “When I informed Ibn ‘Abbas of what ‘Aisha had said, he asked me whether I knew who was the second man whom ‘Aisha had not named. I replied in the negative. He said, ‘He was ‘Ali bin Abi Talib.”