Sahih al-Bukhari 681

It is related that Anas said, "The Prophet, may Allah bless him and grant him peace, did not come out for three days. Once after the iqama for the prayer had been given, Abu Bakr went forward." He continued, "The Prophet of Allah, may Allah bless him and grant him peace, took hold of the curtain and lifted it. No sight could have been more pleasing to us than the face of the Prophet, may Allah bless him and grant him peace, when his face appeared before us. The Prophet, may Allah bless him and grant him peace, indicated with his hand to Abu Bakr to go forward. Then the Prophet, may Allah bless him and grant him peace, let the curtain drop and we did not see him again until he died."