كتاب الأذان
Read the English translation first, with the original Arabic directly underneath.
Narrated An-Nu`man bin 'Bashir:
The Prophet (ﷺ) said, "Straighten your rows or Allah will alter your faces."
لَتُسَوُّنَّ صُفُوفَكُمْ أَوْ لَيُخَالِفَنَّ اللَّهُ بَيْنَ وُجُوهِكُمْ