It is recommended to fast three days of every month, and to fast on the days of 'Arafah and 'Ashura', and to fast on Mondays and Thursdays

Mu'adha al-'Adawiyya reported that she asked 'A'isha, the wife of the Apostle of Allah ﷺ, whether the Messenger of Allah ﷺ observed fasts for three days during every month. She said: Yes I said to her: Which were (the particular) days of the month on which he observed fast? She said: He was not particular about the days of the month on which to observe fast.

حَدَّثَنَا شَيْبَانُ بْنُ فَرُّوخَ، حَدَّثَنَا عَبْدُ الْوَارِثِ، عَنْ يَزِيدَ الرِّشْكِ، قَالَ حَدَّثَتْنِي مُعَاذَةُ، الْعَدَوِيَّةُ أَنَّهَا سَأَلَتْ عَائِشَةَ زَوْجَ النَّبِيِّ ﷺ أَكَانَ رَسُولُ اللَّهِ ﷺ يَصُومُ مِنْ كُلِّ شَهْرٍ ثَلاَثَةَ أَيَّامٍ قَالَتْ نَعَمْ . فَقُلْتُ لَهَا مِنْ أَىِّ أَيَّامِ الشَّهْرِ كَانَ يَصُومُ قَالَتْ لَمْ يَكُنْ يُبَالِي مِنْ أَىِّ أَيَّامِ الشَّهْرِ يَصُومُ .

'Imran b. Husain (Allah be pleased with them) reported that the Apostle of Allah ﷺ said to him (or he said to another person and he was listening to it): O, so and so, did you observe fast in the middle of the month? He said: No. Thereupon he (the Messenger of Allah) said: When you break it, then observe fast for two days.

وَحَدَّثَنِي عَبْدُ اللَّهِ بْنُ مُحَمَّدِ بْنِ أَسْمَاءَ الضُّبَعِيُّ، حَدَّثَنَا مَهْدِيٌّ، - وَهُوَ ابْنُ مَيْمُونٍ - حَدَّثَنَا غَيْلاَنُ بْنُ جَرِيرٍ، عَنْ مُطَرِّفٍ، عَنْ عِمْرَانَ بْنِ حُصَيْنٍ، - رضى الله عنهما - أَنَّﷺ قَالَ لَهُ أَوْ قَالَ لِرَجُلٍ وَهُوَ يَسْمَعُ " يَا فُلاَنُ أَصُمْتَ مِنْ سُرَّةِ هَذَا الشَّهْرِ " . قَالَ لاَ . قَالَ " فَإِذَا أَفْطَرْتَ فَصُمْ يَوْمَيْنِ " .

Abu Qatada reported that a person came to the Apostle of Allah ﷺ and said: How do you observe fast? The Messenger of Allah ﷺ felt annoyed. 1560 When 'Umar (Allah be pleased with him) noticed his annoyance, he said: We are well pleased with Allah as our Lord, with Islam as our Code of Life, and with Muhammad as our Prophet. We seek refuge with Allah from the anger of Allah and that of His Messenger. 'Umar kept on repeating these words till his (the Prophet's) anger calmed down. Then Umar said: Messenger of Allah. what is the position of one who perpetually observes fasts? Thereupon he said: He neither fasted nor broke it, or he said: He did not fast and he did not break it. He said: What about him who observes fast for two days and breaks one day. There- upon he said: Is anyone capable of doing it? He ('Umar) said: What is the position of him who observes fast for a day and breaks on the other day? Thereupon he (the Holy Prophet) said: That is the fast of David ﷺ. He ('Umar) said: What about him who observes fast one day and breaks it for two days. Thereupon he (the Messenger of Allah) said: I wish, I were given strength to observe that. Thereafter he said: The observance of three days' fast every Month and that of Ramadan every year is a perpetual fasting. I seek from Allah that fasting on the day of 'Arafa may atone for the sins of the preceding and the coming years. and I seek from Allah that fasting on the day of Ashura may atone for the sins of the preceding year.

وَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى التَّمِيمِيُّ، وَقُتَيْبَةُ بْنُ سَعِيدٍ، جَمِيعًا عَنْ حَمَّادٍ، - قَالَ يَحْيَى أَخْبَرَنَا حَمَّادُ بْنُ زَيْدٍ، - عَنْ غَيْلاَنَ، عَنْ عَبْدِ اللَّهِ بْنِ مَعْبَدٍ الزِّمَّانِيِّ، عَنْ أَبِي قَتَادَةَ، رَجُلٌ أَتَى النَّبِيَّ ﷺ فَقَالَ كَيْفَ تَصُومُ فَغَضِبَ رَسُولُ اللَّهِ ﷺ فَلَمَّا رَأَى عُمَرُ - رضى الله عنه - غَضَبَهُ قَالَ رَضِينَا بِاللَّهِ رَبًّا وَبِالإِسْلاَمِ دِينًا وَبِمُحَمَّدٍ نَبِيًّا نَعُوذُ بِاللَّهِ مِنْ غَضَبِ اللَّهِ وَغَضَبِ رَسُولِهِ . فَجَعَلَ عُمَرُ - رضى الله عنه - يُرَدِّدُ هَذَا الْكَلاَمَ حَتَّى سَكَنَ غَضَبُهُ فَقَالَ عُمَرُ يَا رَسُولَ اللَّهِ كَيْفَ بِمَنْ يَصُومُ الدَّهْرَ كُلَّهُ قَالَ " لاَ صَامَ وَلاَ أَفْطَرَ - أَوْ قَالَ - لَمْ يَصُمْ وَلَمْ يُفْطِرْ " . قَالَ كَيْفَ مَنْ يَصُومُ يَوْمَيْنِ وَيُفْطِرُ يَوْمًا قَالَ " وَيُطِيقُ ذَلِكَ أَحَدٌ " . قَالَ كَيْفَ مَنْ يَصُومُ يَوْمًا وَيُفْطِرُ يَوْمًا قَالَ " ذَاكَ صَوْمُ دَاوُدَ عَلَيْهِ السَّلاَمُ " . قَالَ كَيْفَ مَنْ يَصُومُ يَوْمًا وَيُفْطِرُ يَوْمَيْنِ قَالَ " وَدِدْتُ أَنِّي طُوِّقْتُ ذَلِكَ " . ثُمَّ قَالَ رَسُولُ اللَّهِ ﷺ " ثَلاَثٌ مِنْ كُلِّ شَهْرٍ وَرَمَضَانُ إِلَى رَمَضَانَ فَهَذَا صِيَامُ الدَّهْرِ كُلِّهِ صِيَامُ يَوْمِ عَرَفَةَ أَحْتَسِبُ عَلَى اللَّهِ أَنْ يُكَفِّرَ السَّنَةَ الَّتِي قَبْلَهُ وَالسَّنَةَ الَّتِي بَعْدَهُ وَصِيَامُ يَوْمِ عَاشُورَاءَ أَحْتَسِبُ عَلَى اللَّهِ أَنْ يُكَفِّرَ السَّنَةَ الَّتِي قَبْلَهُ " .

Abu Qatada al-Ansari (Allah be pleased with him) reported that the Messenger of Allah ﷺ was asked about his fasting. The Messenger of Allah ﷺ felt annoyed. Thereupon 'Umar (Allah be pleased with him) said: We are pleased with Allah as the Lord, with Islam as our Code of Life, with Muhammad as the Messenger and with our pledge (to you for willing and cheerful submission) as a (sacred) commitment. He was then asked about perpetual fasting, whereupon he said: He neither fasted nor did he break it, or he did not fast and he did not break it. He was then asked about fasting for two days and breaking one day. He (the Holy Prophet) said: And who has strength enough to do it? He was asked about fasting for a day and breaking for two days, whereupon he said: May Allah bestow upon us strength to do it. He was then asked about fasting for a day and breaking on the other, whereupon he said: That is the fasting of my brother David ﷺ. He was then asked about fasting on Monday, whereupon he said: It was the day on which I was born. on which I was commissioned with prophethood or revelation was sent to me, (and he further) said: Three days' fasting every month and of the whole of Ramadan every year is a perpetual fast. He was asked about fasting on the day of 'Arafa (9th of Dhu'I-Hijja), whereupon he said: It expiates the sins of the preceding year and the coming year. He was asked about fasting on the day of 'Ashura (10th of Muharram), whereupon be said: It expiates the sins of the preceding year. (Imam Muslim said that in this hadith there is a) narration of Imam Shu'ba that he was asked about fasting on Monday and Thursday, but we (Imam Muslim) did not mention Thursday for we found it as an error (in reporting).

حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، وَمُحَمَّدُ بْنُ بَشَّارٍ، - وَاللَّفْظُ لاِبْنِ الْمُثَنَّى - قَالاَ حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، عَنْ غَيْلاَنَ بْنِ جَرِيرٍ، سَمِعَ عَبْدَ اللَّهِ بْنَ مَعْبَدٍ الزِّمَّانِيَّ، عَنْ أَبِي قَتَادَةَ الأَنْصَارِيِّ، رضى الله عنه أَنَّ رَسُولَ اللَّهِ ﷺ سُئِلَ عَنْ صَوْمِهِ قَالَ فَغَضِبَ رَسُولُ اللَّهِ ﷺ فَقَالَ عُمَرُ رضى الله عنه رَضِينَا بِاللَّهِ رَبًّا وَبِالإِسْلاَمِ دِينًا وَبِمُحَمَّدٍ رَسُولاً وَبِبَيْعَتِنَا بَيْعَةً . قَالَ فَسُئِلَ عَنْ صِيَامِ الدَّهْرِ فَقَالَ " لاَ صَامَ وَلاَ أَفْطَرَ " . أَوْ " مَا صَامَ وَمَا أَفْطَرَ " . قَالَ فَسُئِلَ عَنْ صَوْمِ يَوْمَيْنِ وَإِفْطَارِ يَوْمٍ قَالَ " وَمَنْ يُطِيقُ ذَلِكَ " . قَالَ وَسُئِلَ عَنْ صَوْمِ يَوْمٍ وَإِفْطَارِ يَوْمَيْنِ قَالَ " لَيْتَ أَنَّ اللَّهَ قَوَّانَا لِذَلِكَ " . قَالَ وَسُئِلَ عَنْ صَوْمِ يَوْمٍ وَإِفْطَارِ يَوْمٍ قَالَ " ذَاكَ صَوْمُ أَخِي دَاوُدَ عَلَيْهِ السَّلاَمُ " . قَالَ وَسُئِلَ عَنْ صَوْمِ يَوْمِ الاِثْنَيْنِ قَالَ " ذَاكَ يَوْمٌ وُلِدْتُ فِيهِ وَيَوْمٌ بُعِثْتُ أَوْ أُنْزِلَ عَلَىَّ فِيهِ " . قَالَ فَقَالَ " صَوْمُ ثَلاَثَةٍ مِنْ كُلِّ شَهْرٍ وَرَمَضَانَ إِلَى رَمَضَانَ صَوْمُ الدَّهْرِ " . قَالَ وَسُئِلَ عَنْ صَوْمِ يَوْمِ عَرَفَةَ فَقَالَ " يُكَفِّرُ السَّنَةَ الْمَاضِيَةَ وَالْبَاقِيَةَ " . قَالَ وَسُئِلَ عَنْ صَوْمِ يَوْمِ عَاشُورَاءَ فَقَالَ " يُكَفِّرُ السَّنَةَ الْمَاضِيَةَ " . وَفِي هَذَا الْحَدِيثِ مِنْ رِوَايَةِ شُعْبَةَ قَالَ وَسُئِلَ عَنْ صَوْمِ يَوْمِ الاِثْنَيْنِ وَالْخَمِيسِ فَسَكَتْنَا عَنْ ذِكْرِ الْخَمِيسِ لَمَّا نَرَاهُ وَهْمًا .

This hadith has been narrated by Shu'ba with the same chain of transmitters.

وَحَدَّثَنَاهُ عُبَيْدُ اللَّهِ بْنُ مُعَاذٍ، حَدَّثَنَا أَبِي ح، وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا شَبَابَةُ، ح وَحَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، أَخْبَرَنَا النَّضْرُ بْنُ شُمَيْلٍ، كُلُّهُمْ عَنْ شُعْبَةَ، بِهَذَا الإِسْنَادِ.

This hadith has been narrated by Ghailan b. Jarir with the same chain of transmitters, but with one variation, that there has been made mention of Monday and not of Thursday.

وَحَدَّثَنِي أَحْمَدُ بْنُ سَعِيدٍ الدَّارِمِيُّ، حَدَّثَنَا حَبَّانُ بْنُ هِلاَلٍ، حَدَّثَنَا أَبَانُ الْعَطَّارُ، حَدَّثَنَا غَيْلاَنُ بْنُ جَرِيرٍ، فِي هَذَا الإِسْنَادِ بِمِثْلِ حَدِيثِ شُعْبَةَ غَيْرَ أَنَّهُ ذَكَرَ فِيهِ الاِثْنَيْنِ وَلَمْ يَذْكُرِ الْخَمِيسَ .