عن أنس بن مالك رضي الله عنه قال: قال رسول الله صلى الله عليه وسلم : «سَوُّوا صُفُوفَكُم، فإِنَّ تَسوِيَة الصُّفُوف من تَمَام الصَّلاَة».
[صحيح] - [متفق عليه]
Anas ibn Mālik (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "Straighten your rows, for indeed, straightening the rows is part of the perfection of the prayer."
Sahih/Authentic. - [Al-Bukhari and Muslim]
The Prophet (may Allah's peace and blessings be upon him) guides his nation to what ensures their welfare and success. Here, he commands them to straighten their rows in prayer so that they would all face the Qiblah in the same manner and close the gaps in the rows so as to not give the devil a way to tamper with their prayer. He also taught them some of the benefits that they would gain by straightening the rows; that it is a sign of the perfection and completion of the prayer and that crookedness in the row is a flaw and defect in the prayer.