Sunan Ibn Majah 1736
سنن ابن ماجه#1736Sahihحَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، حَدَّثَنَا وَكِيعٌ، عَنِ ابْنِ أَبِي ذِئْبٍ، عَنِ الْقَاسِمِ بْنِ عَبَّاسِ، عَنْ عَبْدِ اللَّهِ بْنِ عُمَيْرٍ، مَوْلَى ابْنِ عَبَّاسٍ عَنِ ابْنِ عَبَّاسٍ، قَالَ: قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " لَئِنْ بَقِيتُ إِلَى قَابِلٍ لأَصُومَنَّ الْيَوْمَ التَّاسِعَ " .
It was narrated from Ibn ‘Abbas that the Messenger of Allah (ﷺ) said:“If I live until next year, I will fast the ninth day (of Muharram) too.”
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:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih Muslim
In-book reference: 7:99