Sahih al-Bukhari 4737
صحيح البخاري#4737Sahihحَدَّثَنِي يَعْقُوبُ بْنُ إِبْرَاهِيمَ، حَدَّثَنَا رَوْحٌ، حَدَّثَنَا شُعْبَةُ، حَدَّثَنَا أَبُو بِشْرٍ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ لَمَّا قَدِمَ رَسُولُ اللَّهِ صلى الله عليه وسلم الْمَدِينَةَ، وَالْيَهُودُ تَصُومُ عَاشُورَاءَ، فَسَأَلَهُمْ، فَقَالُوا هَذَا الْيَوْمُ الَّذِي ظَهَرَ فِيهِ مُوسَى عَلَى فِرْعَوْنَ، فَقَالَ النَّبِيُّ صلى الله عليه وسلم " نَحْنُ أَوْلَى بِمُوسَى مِنْهُمْ فَصُومُوهُ ".
Narrated Ibn `Abbas:When Allah's Messenger (ﷺ) arrived at Medina, he found the Jews observing the fast on the day of 'Ashura' (10th of Muharram). The Prophet (ﷺ) asked them (about it) and they replied, "This is the day when Moses became victorious over Pharaoh." The Prophet (ﷺ) said (to the Muslims), "We are nearer to Moses than they, so fast on this day
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: 65:259