Hadith: Arabic Text followed by English Translation.
عَنْ أَبِي قَتَادَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ
صِيَامُ يَوْمِ عَاشُورَاءَ إِنِّي أَحْتَسِبُ عَلَى اللَّهِ أَنْ يُكَفِّرَ السَّنَةَ الَّتِي قَبْلَهُ
رواه الترمذي (٧٥٢) و ابن ماجه ١٧٣٨ وصححه الألباني في “صحيح الترمذي”
Abu Qatadah narrated that :The Prophet said (ﷺ) :
Fast the Day of Ashura*, for indeed I anticipate that Allah will forgive (the sins of) the year before it.
Narrated by Tirmidhi, 752 and Ibn Majah, 1738 and Classed as Saheeh by Albani in Saheeh Tirmidhi.
*Ashura is the 10th Day of Muharram (The first month of the Hijri Islamic Calendar).
It is also recommended to fast on the 9th of Muharram based on the Hadith below:
Hadith
عَبْدَ اللَّهِ، بْنَ عَبَّاسٍ – رضى الله عنهما – يَقُولُ حِينَ صَامَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَوْمَ عَاشُورَاءَ وَأَمَرَ بِصِيَامِهِ قَالُوا يَا رَسُولَ اللَّهِ إِنَّهُ يَوْمٌ تُعَظِّمُهُ الْيَهُودُ وَالنَّصَارَى . فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم
فَإِذَا كَانَ الْعَامُ الْمُقْبِلُ – إِنْ شَاءَ اللَّهُ – صُمْنَا الْيَوْمَ التَّاسِعَ ”
قَالَ فَلَمْ يَأْتِ الْعَامُ الْمُقْبِلُ حَتَّى تُوُفِّيَ رَسُولُ اللَّهِ صلى الله عليه وسلم
رواه مسلم ١١٣٤
Ibn ‘Abbas reported that when the Messenger of Allah (ﷺ) fasted on the day of ‘Ashura and commanded that it should he observed as a fast, they (his Companions) said to him:
Messenger of Allah, it is a day which the Jews and Christians hold in high esteem. Thereupon the Messenger of Allah (ﷺ) said:
When the next year comes, God willing, we would observe fast on the 9th But the Messenger of Allah (ﷺ) died before the advent of the next year.
Sahih Muslim 1134
*For the actual dates please confirm with your Local Masjid because dates may vary based on Moonsighting.