Sahih Muslim Book 4, Hadith Number 836.

Chapter : The Muqtadi (follower) should strictly follow the Imam in prayer.

‘Aisha reported: When the Messenger of Allah (may peace be upon him) came to my house, he said: Ask Abu Bakr to lead people in prayer. ‘Aisha narrated: I said, Messenger of Allah, Abu Bakr is a man of tenderly feelings; as he recites the Qur’an, he cannot help shedding tears: so better command anyone else to lead the prayer. By Allah, there is nothing disturbing in it for me but the idea that the people may not take evil omen with regard to one who is the first to occupy the place of the Messenger of Allah (may peace be upon him). I tried to dissuade him (the Holy Prophet) twice or thrice (from appointing my father as an Imam in prayer), but he ordered Abu Bakr to lead the people in prayer and said: You women are like those (who had) surrounded Yusuf.