Sunan at-Tirmithiy كتاب الصوم باب ما جاء فى صوم المحرم

حَدَّثَنَا عَلِىُّ بْنُ حُجْرٍ قَالَ أَخْبَرَنَا عَلِىُّ بْنُ مُسْهِرٍ عَنْ عَبْدِ الرَّحْمَنِ بْنِ إِسْحَاقَ عَنِ النُّعْمَانِ بْنِ سَعْدٍ عَنْ عَلِىٍّ قَالَ سَأَلَهُ رَجُلٌ فَقَالَ أَىُّ شَهْرٍ تَأْمُرُنِى أَنْ أَصُومَ بَعْدَ شَهْرِ رَمَضَانَ قَالَ لَهُ مَا سَمِعْتُ أَحَدًا يَسْأَلُ عَنْ هَذَا إِلاَّ رَجُلاً سَمِعْتُهُ يَسْأَلُ رَسُولَ اللَّهِ صلى الله عليه وسلم وَأَنَا قَاعِدٌ فَقَالَ يَا رَسُولَ اللَّهِ أَىُّ شَهْرٍ تَأْمُرُنِى أَنْ أَصُومَ بَعْدَ شَهْرِ رَمَضَانَ قَالَ إِنْ كُنْتَ صَائِمًا بَعْدَ شَهْرِ رَمَضَانَ فَصُمِ الْمُحَرَّمَ فَإِنَّهُ شَهْرُ اللَّهِ فِيهِ يَوْمٌ تَابَ اللَّهُ فِيهِ عَلَى قَوْمٍ وَيَتُوبُ فِيهِ عَلَى قَوْمٍ آخَرِينَ. قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ غَرِيبٌ.
A man asked the Messenger of God, peace and blessings of God be upon him, "Which month do you instruct me to fast after the month of Ramaḍān?" He (the Messenger of God) replied, "If you are to fast beyond the month of Ramaḍān, then fast [in the month of] Muḥarram, for it is indeed the month of God; it includes a day in which God has forgiven a people (1), and in which he forgives other people (2)." Footnotes: (1) The Prophet, peace and blessings of God be upon him, is referring to the followers of prophet Moses, peace be upon him, whom God forgave on the tenth day of Muḥarram (the first month of the Islamic calendar) and saved them on that day from their enemy, Pharaoh. Scholars say the Prophet, peace and blessings of God be upon him may have also meant prophet Ādam or the followers of prophet Jonah, who were also forgiven on the same day. (2) God will continue to forgive more people or nations on every annual occurrence of that day. That day is the tenth of Muḥarram; the Arabic name for the holiday is 'Āshūra'. Click on ḥadīth to read more