Sahih Muslim 924
صحيح مسلم#924Sahihحَدَّثَنَا ابْنُ أَبِي عُمَرَ، حَدَّثَنَا مَعْنُ بْنُ عِيسَى، عَنْ مَالِكِ بْنِ أَنَسٍ، عَنِ الزُّهْرِيِّ، عَنْ أَنَسٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم رَكِبَ فَرَسًا فَصُرِعَ عَنْهُ فَجُحِشَ شِقُّهُ الأَيْمَنُ . بِنَحْوِ حَدِيثِهِمْ وَفِيهِ " إِذَا صَلَّى قَائِمًا فَصَلُّوا قِيَامًا " .
Anas reported:The Messenger of Allah (ﷺ) rode a horse and fell down from it and his right side was grazed, and the rest of the hadith is the same, and (these words) are found in it:" When he (the Imam) says prayer in an erect posture, you should also say it in an erect posture
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: 4:86