Sahih Muslim 977
صحيح مسلم#977Sahihحَدَّثَنَا مُحَمَّدُ بْنُ رَافِعٍ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، حَدَّثَنَا مَعْمَرٌ، عَنْ هَمَّامِ بْنِ مُنَبِّهٍ، قَالَ هَذَا مَا حَدَّثَنَا أَبُو هُرَيْرَةَ، عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم فَذَكَرَ أَحَادِيثَ مِنْهَا وَقَالَ " أَقِيمُوا الصَّفَّ فِي الصَّلاَةِ فَإِنَّ إِقَامَةَ الصَّفِّ مِنْ حُسْنِ الصَّلاَةِ " .
Hammam b. Munabbih reported:This is what was transmitted to us by Abu Huraira from the Messenger of Allah (ﷺ) and, while making a mention of a few ahadith, said: (The Messengerof Allah directed us thus): Establish rows in prayer, for the making of a row (straight) is one of the merits of prayer
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:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 4:139