Sahih al-Bukhari 1207
صحيح البخاري#1207Sahihحَدَّثَنَا أَبُو نُعَيْمٍ، حَدَّثَنَا شَيْبَانُ، عَنْ يَحْيَى، عَنْ أَبِي سَلَمَةَ، قَالَ حَدَّثَنِي مُعَيْقِيبٌ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ فِي الرَّجُلِ يُسَوِّي التُّرَابَ حَيْثُ يَسْجُدُ قَالَ " إِنْ كُنْتَ فَاعِلاً فَوَاحِدَةً ".
Narrated Mu'aiqib:The Prophet (ﷺ) talked about a man leveling the earth on prostrating, and said, "If you have to do so, then do it once
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 al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 21:11