Sahih al-Bukhari 1818
صحيح البخاري#1818Sahihوَعَنْ مُحَمَّدِ بْنِ يُوسُفَ، حَدَّثَنَا وَرْقَاءُ، عَنِ ابْنِ أَبِي نَجِيحٍ، عَنْ مُجَاهِدٍ، أَخْبَرَنَا عَبْدُ الرَّحْمَنِ بْنُ أَبِي لَيْلَى، عَنْ كَعْبِ بْنِ عُجْرَةَ ـ رضى الله عنه ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم رَآهُ، وَقَمْلُهُ يَسْقُطُ عَلَى وَجْهِهِ. مِثْلَهُ.
Narrated Ka'b bin 'Ujra (ra):Allah's Messenger (ﷺ) saw him (i.e. Ka'b) while the lice were falling on his face
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: 27:13