Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
ahmad:19721Yūnus b. Muḥammad > Abū Laylá ʿAbdullāh b. Maysarah > Mazīdah b. Jābir

[Machine] "My mother and I were in the Mosque of Kufa during the caliphate of Uthman, and Abu Musa al-Ash'ari was with us. He said, 'I heard him saying that the Messenger of Allah ﷺ commanded the observance of fasting on the day of Ashura, so fast.'"  

أحمد:١٩٧٢١حَدَّثَنَا يُونُسُ بْنُ مُحَمَّدٍ قَالَ حَدَّثَنَا أَبُو لَيْلَى عَبْدُ اللهِ بْنُ مَيْسَرَةَ عَنْ مَزِيدَةَ بْنِ جَابِرٍ قَالَ قَالَتْ

أُمِّي كُنْتُ فِي مَسْجِدِ الْكُوفَةِ فِي خِلَافَةِ عُثْمَانَ وَعَلَيْنَا أَبُو مُوسَى الْأَشْعَرِيُّ قَالَ فَسَمِعَتْهُ يَقُولُ إِنَّ رَسُولَ اللهِ ﷺ أَمَرَ بِصَوْمِ عَاشُورَاءَ فَصُومُوا