An-Nu‘man b. Bashir said

Allah's Messenger ﷺ used to straighten our rows as if he were trying to make them as straight as arrows until he saw that we had learned it from him. One day he came out, stood up, and was just about to say Allah is most great ’ when he saw a man whose chest projected from the row, so he said, “Servants of Allah, you must straighten your rows, or Allah will certainly put your faces in contrary directions."* * The use of “faces” here may mean the people themselves and their inner nature. The tradition may refer to civil strife, which is possibly the meaning of the tradition below from Abu Mas'ud. Muslim transmitted it.