Sahih Bukhari Volume 005, Book 059, Hadith Number 729.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 59. Military Expeditions Led by the Prophet (PBUH) (Al-Maghaazi)
Narrated By Anas bin Malik : While the Muslims were offering the Fajr prayer on Monday and Abu Bakr was leading them in prayer, suddenly Allah's Apostle lifted the curtain of 'Aisha's dwelling and looked at them while they were in the rows of the prayers and smiled. Abu Bakr retreated to join the row, thinking that Allah's Apostle wanted to come out for the prayer. The Muslims were about to be put to trial in their prayer (i.e. were about to give up praying) because of being overjoyed at seeing Allah's Apostle. But Allah's Apostle beckoned them with his hand to complete their prayer and then entered the dwelling and let fall the curtain.