The Messenger of Allah ﷺ led us in prayer. He noticed a man whose chest was protruding out from the row, so he said, "Straighten your rows and do not differ, for if you do, your hearts will differ."
حدثنا وكيع عن سفيان عن سماك
صلى بنا رسول الله ﷺ فرأى رجلا خارجا صدره من الصف فقال استووا ولا تختلفوا فتختلف قلوبكم
No references are available.
Its isnad is sahih, mentioned previously at 18339.