Nu'man bin Bashir reported: The Messenger of Allah ( صلی اللہ علیہ وسلم ) (may peace-be upon him) used to straighten our rows as if he were straightening an arrow with their help until be saw that we had learnt it from him. One day he came out, stood up (for prayer) and was about to say: Allah is the Greatest, when he saw a man, whose chest was bulging out from the row, so he said: Servants of Allah, you should straighten your rows or Allah would create dissension amongst you.