Al-Kāfi - Volume 4 > Fasting on Ninth of Dhul Hajjah and on Tenth of Muharram
Hadith #2

2ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنِ ابْنِ فَضَّالٍ عَنْ ثَعْلَبَةَ بْنِ مَيْمُونٍ عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ قَالَ سَمِعْتُ أَبَا جَعْفَرٍ (عَلَيْهِ السَّلاَم) يَقُولُ إِنَّ رَسُولَ الله (صلَّى اللهُ عَلَيْهِ وَآلِه) لَمْ يَصُمْ يَوْمَ عَرَفَةَ مُنْذُ نَزَلَ صِيَامُ شَهْرِ رَمَضَانَ.

2. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad, from ibn Faddal from Tha’labah ibn Maymun from Muhammad ibn Muslim who has said the following: ““I once heard abu Ja‘far, ‘Alayhi al-Salam, say, ‘The Messenger of Allah did not fast on the day of ‘Arafah from the time fasting of the month of Ramadan came down.’”