Sahih Muslim 1128
Sahih Muslim · Book 13: The Book of Fasting · Fasting on the day of Ashura'
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ ، حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ مُوسَى ، أَخْبَرَنَا شَيْبَانُ ، عَنْ أَشْعَثَ، بْنِ أَبِي الشَّعْثَاءِ عَنْ جَعْفَرِ بْنِ أَبِي ثَوْرٍ ، عَنْ جَابِرِ بْنِ سَمُرَةَ ، - رضى الله عنه - قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَأْمُرُنَا بِصِيَامِ يَوْمِ عَاشُورَاءَ وَيَحُثُّنَا عَلَيْهِ وَيَتَعَاهَدُنَا عِنْدَهُ فَلَمَّا فُرِضَ رَمَضَانُ لَمْ يَأْمُرْنَا وَلَمْ يَنْهَنَا وَلَمْ يَتَعَاهَدْنَا عِنْدَهُ .
Jabir b Samura reported that the Messenger of Allah (ﷺ) commanded us to observe fast on the day of Ashura and exhorted us to do it and was particular about it But when (fasting) in Ramadan was made obligatory, he hence. forth neither commanded us nor forbade us, nor was he so particular about it.