Hadith 1129 a - The Book of Fasting - Sahih Muslim - صحيح مسلم - Collection of Actions, Sayings and Teachings of Prophet Muhammad (صلى الله عليه و سلم) - Kutub as-Sittah

13. The Book of Fasting - كتاب الصيام

19) Chapter: Fasting on the day of Ashura'

Abd al-Rahman reported that he heard Mu'awiya b. Abu Sufyan delivering a sermon in Medina. i. e. when he came there (for Hajj). He delivered a sermon on the day of 'Ashura and said:

People of Medina, where are your scholars? I heard the Messenger of Allah (ﷺ) say on this very day: It is the day of 'Ashura. Allah has not made fasting on This day obligatory for you but I am fasting. He who likes to observe fast among you should do so, and he who likes not to observe it may not observe it.

Reference: 1129 a
English reference: Book 6, Hadith 2515
In-book reference: Book 13, Hadith 159
Grade: Sahih
Read this hadith from Darussalam Collection

19) باب صَوْمِ يَوْمِ عَاشُورَاءَ ‏‏

حَدَّثَنِي حَرْمَلَةُ بْنُ يَحْيَى، أَخْبَرَنَا ابْنُ وَهْبٍ، أَخْبَرَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، أَخْبَرَنِي حُمَيْدُ بْنُ عَبْدِ الرَّحْمَنِ، أَنَّهُ سَمِعَ مُعَاوِيَةَ بْنَ أَبِي سُفْيَانَ، خَطِيبًا بِالْمَدِينَةِ - يَعْنِي فِي قَدْمَةٍ قَدِمَهَا - خَطَبَهُمْ يَوْمَ عَاشُورَاءَ فَقَالَ أَيْنَ عُلَمَاؤُكُمْ يَا أَهْلَ الْمَدِينَةِ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ لِهَذَا الْيَوْمِ ‏‏ ‏.‏ "‏ هَذَا يَوْمُ عَاشُورَاءَ وَلَمْ يَكْتُبِ اللَّهُ عَلَيْكُمْ صِيَامَهُ وَأَنَا صَائِمٌ فَمَنْ أَحَبَّ مِنْكُمْ أَنْ يَصُومَ فَلْيَصُمْ وَمَنْ أَحَبَّ أَنْ يُفْطِرَ فَلْيُفْطِرْ ‏"