A man prayed behind the row by himself, so the Prophet ﷺ ordered him to repeat the prayer.
حدثنا محمد بن بشار حدثنا محمد بن جعفر حدثنا شعبة عن عمرو بن مرة عن هلال بن يساف عن عمرو بن راشد
أن رجلا صلى خلف الصف وحده فأمره النبي ﷺ أن يعيد الصلاة
[Its chain of transmission is sahih] Abu Dawud narrated it in H: 682 from the hadith of Shubah, transmitted via the same route, and Ibn Hibban graded it sahih in H: 403. See the preceding hadith from him. * Waki's statement is correct.