Sahih al-Bukhari 664

It is related that al-Aswad said, "We were with 'A'isha and we discussed being constant in the prayers and honouring them. She said, 'When the Messenger of Allah, may Allah bless him and grant him peace, was ill with the illness from which he died and it was time for the prayer and the adhan was given, he said, "Tell Abu Bakr to lead the people in prayer. He was told, "Abu Bakr is a tender-hearted man. If he stands in your place, he will not be able to lead the people in the prayer." He repeated what he had said and they repeated what they had said. He repeated it a third time and said, "You are the companions of Yusuf! Tell Abu Bakr to lead the people in prayer." So Abu Bakr came out and prayed. The Messenger of Allah, may Allah bless him and grant him peace, felt better and came out walking between two men. It is as if I could see his legs dragging because of the pain of the illness. Abu Bakr wanted to draw back and the Prophet, may Allah bless him and grant him peace, indicated to him, "Stay in your place." Then he was brought until he sat beside him.' " Al-A'mash was asked "Was the Prophet, may Allah bless him and grant him peace, praying with Abu Bakr following his prayer and the people praying following the prayer of Abu Bakr." He indicated yes with his head Part of it is related from al-A'mash. Abu Mu'awiya added, "He sat to the left of Abu Bakr and Abu Bakr prayed standing."