Sahih al-Bukhari 2514
صحيح البخاري#2514Sahihحَدَّثَنَا خَلاَّدُ بْنُ يَحْيَى، حَدَّثَنَا نَافِعُ بْنُ عُمَرَ، عَنِ ابْنِ أَبِي مُلَيْكَةَ، قَالَ كَتَبْتُ إِلَى ابْنِ عَبَّاسٍ فَكَتَبَ إِلَىَّ أَنَّ النَّبِيَّ صلى الله عليه وسلم قَضَى أَنَّ الْيَمِينَ عَلَى الْمُدَّعَى عَلَيْهِ.
Narrated Ibn Abu Mulaika:I wrote a letter to Ibn `Abbas and he wrote to me that the Prophet (ﷺ) had given the verdict that the defendant had to take an oath
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: 48:7