on saturday or on sunday, the prophet [pbuh] felt that he was well enough to perform the prayer; so he went out leaning on two men in order to perform the noon prayer. abu bakr, who was then about to lead the prayer withdrew when he saw him coming; but the prophet [pbuh] made him a gesture to stay where he was and said: "seat me next to him." they seated him on the left hand side of abu bakr. the prophet [pbuh] led the prayer, and abu bakr followed him and raised his voice at every ‘allâhu akbar’ (i.e. allâh is the greatest) the prophet [pbuh] said, so that the people may hear clearly. [sahih al-bukhari 1/98,99]