Sahih Muslim Book 4, Hadith Number 1361.

Chapter : Disapproval of delaying the prayer from the prescribes time; what one who is led in prayer should do when the Imam delays it ?.

Abu Huraira reported Allah’s Apostle (may peace be upon him) as saying: Prayer said in a congregation is twenty-five degrees more excellent than prayer said by a single person. He (Abu Huraira further) said: The angels of the night and the angels of the day meet together. Abu Huraira said: Recite it you like: “Surely the recital of the Qur’an at dawn is witnessed” (Al-Qur’an, xvii. 78).