Why do you stand in rows as the angels do in the presence of their Lord? We asked: how do the angles stand in rows in the presence of their Lord? He replied: they make the first row complete and keep close together in the row. (Using translation from Abū Dāʾūd 661)
قَالَ رَسُولُ اللهِ ﷺ «أَلَا تَصُفُّونَ كَمَا تَصُفُّ الْمَلَائِكَةُ عِنْدَ رَبِّهِمْ؟» قَالُوا يَا رَسُولَ اللهِ وَكَيْفَ تَصُفُّ الْمَلَائِكَةُ عِنْدَ رَبِّهِمِ؟ قَالَ «يُتِمُّونَ الصُّفُوفَ الْمُقَدَّمَةَ وَيَتَرَاصُّونَ فِي الصَّفِّ»