Call to Prayers (Adhaan)
حَدَّثَنَا أَبُو الْوَلِيدِ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " سَوُّوا صُفُوفَكُمْ فَإِنَّ تَسْوِيَةَ الصُّفُوفِ مِنْ إِقَامَةِ الصَّلاَةِ ".Narrated Anas bin Malik:The Prophet (ﷺ) said, "Straighten your rows as the straightening of rows is essential for a perfect and correct prayer
From Sahih al-Bukhari, whose reports the scholars accept as authentic.