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.
ibnhibban:3622Muḥammad b. al-Ḥasan b. al-Khalīl > ʿAbdullāh b. Muʿāwiyah > Ḥammād b. Salamah > ʿUbaydullāh b. ʿUmar > Nāfiʿ > Ibn ʿUmar

[Machine] The Messenger of Allah ﷺ said regarding the fast of the day of Ashura, after the fast of Ramadan was obligated: "Whoever wishes to fast it may do so, and whoever wishes to break his fast may do so."  

ابن حبّان:٣٦٢٢أَخْبَرَنَا مُحَمَّدُ بْنُ الْحَسَنِ بْنِ الْخَلِيلِ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مُعَاوِيَةَ قَالَ حَدَّثَنَا حَمَّادُ بْنُ سَلَمَةَ عَنْ عُبَيْدِ اللَّهِ بْنِ عُمَرَ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ فِي صَوْمِ يَوْمِ عَاشُورَاءَ بَعْدَمَا نَزَلَ صَوْمُ رَمَضَانَ «مَنْ شَاءَ صَامَهُ وَمَنْ شَاءَ أَفْطَرَهُ»