Sahih al-Bukhari 791
صحيح البخاري#791Sahihحَدَّثَنَا حَفْصُ بْنُ عُمَرَ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ سُلَيْمَانَ، قَالَ سَمِعْتُ زَيْدَ بْنَ وَهْبٍ، قَالَ رَأَى حُذَيْفَةُ رَجُلاً لاَ يُتِمُّ الرُّكُوعَ وَالسُّجُودَ قَالَ مَا صَلَّيْتَ، وَلَوْ مُتَّ مُتَّ عَلَى غَيْرِ الْفِطْرَةِ الَّتِي فَطَرَ اللَّهُ مُحَمَّدًا صلى الله عليه وسلم.
Narrated Zaid bin Wahb:Hudhaifa saw a person who was not performing the bowing and prostration perfectly. He said to him, "You have not prayed and if you should die you would die on a religion other than that of Muhammad
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: 10:186