Sahih Bukhari, Chapter: Call to Prayers (Adhaan)

The Prophet said, "No prayer is harder for the hypocrites than the Fajr and the 'Isha' prayers and if they knew the reward for these prayers at their respective times, they would certainly present themselves (in the mosques) even if they had to c awl." The Prophet added, "Certainly I decided to order the Mu'adh-dhin (call-maker) to pronounce Iqama and order a man to lead the prayer and then take a fire flame to burn all those who had not left their houses so far for the prayer along with their houses."