Sunan an-Nasa'i 813
سنن النسائي#813Sahihأَخْبَرَنَا أَبُو بَكْرِ بْنُ نَافِعٍ، قَالَ حَدَّثَنَا بَهْزُ بْنُ أَسَدٍ، قَالَ حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ، عَنْ ثَابِتٍ، عَنْ أَنَسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ يَقُولُ " اسْتَوُوا اسْتَوُوا اسْتَوُوا فَوَالَّذِي نَفْسِي بِيَدِهِ إِنِّي لأَرَاكُمْ مِنْ خَلْفِي كَمَا أَرَاكُمْ مِنْ بَيْنِ يَدَىَّ " .
It was narrated from Anas that the Prophet (ﷺ) used to say:"Make your rows straight, make your rows straight, make your rows straight. By the One in Whose Hand is my soul! I can see you behind me as I can see you in front of me
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 10:37