Authentic Supplication Number 72.
It is reported by way of ‘Anas , that the Prophet said: Sawwoo sufoofakum, fa’inna taswiyatas-sufoofi min iqamatis-salati (87).
(87) Straighten your rows, for the straightening of the rows is [part] of the establishment of salat.
Al-Albani said it was sound, and that it was reported by Al-Bukhari, Muslim, Abu Dawood, and Ibn Majah. It is #3647 in Saheeh Al-Jami` As-Sagheer wa Ziyadatih, and #674 in his Saheeh ‘Abi Dawood.