عَن النُّعْمَانِ بْنِ بَشِيرٍ قَالَ: كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يُسَوِّي صُفُوفَنَا حَتَّى كَأَنَّمَا يُسَوِّي بِهَا الْقِدَاحَ حَتَّى رَأَى أَنَّا قَدْ عَقَلْنَا عَنْهُ ثُمَّ خَرَجَ يَوْمًا فَقَامَ حَتَّى كَادَ أَنْ يُكَبِّرَ فَرَأَى رَجُلًا بَادِيًا صَدْرُهُ مِنَ الصَّفِّ فَقَالَ: «عِبَادَ اللَّهِ لَتُسَوُّنَّ صُفُوفَكُمْ أَوْ لَيُخَالِفَنَّ اللَّهُ بَيْنَ وُجُوهِكُمْ» . رَوَاهُ مُسلم

Abu Mas'ud al-Ansari said

God’s Messenger used to touch our shoulders at the prayer and say, “Keep straight; do not be irregular and so have your hearts irregular. Let those of you who are sedate and prudent be near me, then those who are next to them, then those who are next to them." Abu Mas'ud said, “Nowadays you are much more irregular." Muslim transmitted it.