عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ: ((أَقِيمُوا الصَّفَّ فِي الصَّلَاةِ فَإِنَّ إِقَامَةَ الصَّفِّ مِنْ حُسْنِ الصَّلَاةِ))
Sayyiduna Abu Hurairah (may Allah be pleased with him) reports that the Messenger of Allah (peace and blessings be upon him and his family) said: Straighten and align the rows in prayer, for indeed straightening and aligning the rows is part of the beauty of prayer.