The Messenger of Allah ﷺ used to straighten our rows so precisely that it was as if he were aligning arrows. When he was about to say the opening takbir, he noticed a man whose chest was protruding from the line. He said, "Straighten your rows, or Allah will set your faces against one another."
حدثنا حسين بن علي عن زائدة عن سماك
كان رسول الله ﷺ يسوينا في الصفوف حتى كأنما يحاذي بنا القداح فلما أراد أن يكبر رأى رجلا شاخصا صدره فقال لتسون صفوفكم أو ليخالفن الله بين وجوهكم