كتاب الصيام
13  
The Book of Fasting
(19)
Chapter: Fasting on the day of Ashura'
(19)
باب صَوْمِ يَوْمِ عَاشُورَاءَ ‏‏
Sahih Muslim 1130 b

This hadith has been narrated by Ibn Bishr with the same chain of transmitters (but with a slight variation) that he (the Holy Prophet) inquired of them (Jews) about it (fasting on the day of 'Ashura).

وَحَدَّثَنَاهُ ابْنُ بَشَّارٍ، وَأَبُو بَكْرِ بْنُ نَافِعٍ جَمِيعًا عَنْ مُحَمَّدِ بْنِ جَعْفَرٍ، عَنْ شُعْبَةَ، عَنْ أَبِي بِشْرٍ، بِهَذَا الإِسْنَادِ وَقَالَ فَسَأَلَهُمْ عَنْ ذَلِكَ، ‏.‏
Reference : Sahih Muslim 1130b
In-book reference : Book 13, Hadith 163
USC-MSA web (English) reference : Book 6, Hadith 2519
  (deprecated numbering scheme)