Sahih Muslim 2666
صحيح مسلم#2666Sahihوَحَدَّثَنَا الْحَسَنُ بْنُ عَلِيٍّ الْحُلْوَانِيُّ، حَدَّثَنَا ابْنُ أَبِي مَرْيَمَ، حَدَّثَنَا يَحْيَى بْنُ أَيُّوبَ، حَدَّثَنِي إِسْمَاعِيلُ بْنُ أُمَيَّةَ، أَنَّهُ سَمِعَ أَبَا غَطَفَانَ بْنَ طَرِيفٍ الْمُرِّيَّ، يَقُولُ سَمِعْتُ عَبْدَ اللَّهِ، بْنَ عَبَّاسٍ - رضى الله عنهما - يَقُولُ حِينَ صَامَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَوْمَ عَاشُورَاءَ وَأَمَرَ بِصِيَامِهِ قَالُوا يَا رَسُولَ اللَّهِ إِنَّهُ يَوْمٌ تُعَظِّمُهُ الْيَهُودُ وَالنَّصَارَى . فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " فَإِذَا كَانَ الْعَامُ الْمُقْبِلُ - إِنْ شَاءَ اللَّهُ - صُمْنَا الْيَوْمَ التَّاسِعَ " . قَالَ فَلَمْ يَأْتِ الْعَامُ الْمُقْبِلُ حَتَّى تُوُفِّيَ رَسُولُ اللَّهِ صلى الله عليه وسلم
Ibn 'Abbas reported that when the Messenger of Allah (ﷺ) fasted on the day of 'Ashura and commanded that it should he observed as a fast, they (his Companions) said to him:Messenger of Allah, it is a day which the Jews and Christians hold in high esteem. Thereupon the Messenger of Allah (ﷺ) said: When the next year comes, God willing, we would observe fast on the 9th But the Messenger of Allah (ﷺ) died before the advent of the next year
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 Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 13:172