Sahih Bukhari Volume 1, Book 11, Hadith Number 649
Narated By Anas : The Prophet did not come out for three days. The people stood for the prayer and Abu Bakr went ahead to lead the prayer. (In the meantime) the Prophet caught hold of the curtain and lifted it. When the face of the Prophet appeared we had never seen a scene more pleasing than the face of the Prophet as it appeared then. The Prophet beckoned to Abu Bakr to lead the people in the prayer and then let the curtain fall. We did not see him (again) till he died.