Chapter on Voluntary Fasting and Its Rewards on Different Days

Man Lā Yaḥḍuruh al-Faqīh|Volume 2|Book 2|Chapter 5

Man Lā Yaḥḍuruh al-Faqīh

Volume 2, Book 2, Chapter 5

Chapter on Voluntary Fasting and Its Rewards on Different Days
20 hadiths · 3 commentaries
Hadith 1

سَأَلَ مُحَمَّدُ بْنُ مُسْلِمٍ وَ زُرَارَةُ بْنُ أَعْيَنَ أَبَا جَعْفَرٍ اَلْبَاقِرَ عَلَيْهِ اَلسَّلاَمُ: عَنْ صَوْمِ يَوْمِ عَاشُورَاءَ فَقَالَ «كَانَ صَوْمُهُ قَبْلَ شَهْرِ رَمَضَانَ فَلَمَّا نَزَلَ شَهْرُ رَمَضَانَ تُرِكَ ».

Muhammad ibn Muslim and Zurara ibn A‘yan asked Abu Ja‘far Imam Muhammad ibn Ali Al-Baqir (a.s) about fasting on the Day of Ashura. Imam (a.s) said: "Its fasting was practiced before the Month of Ramadan, but when the Month of Ramadan was prescribed, it was abandoned."

Hadith 2

وَ قَالَ عَلِيٌّ عَلَيْهِ اَلسَّلاَمُ قَالَ رَسُولُ اَللَّهِ صَلَّى اَللَّهُ عَلَيْهِ وَ آلِهِ: «مَنْ صَامَ يَوْماً تَطَوُّعاً أَدْخَلَهُ اَللَّهُ عَزَّ وَ جَلَّ اَلْجَنَّةَ ».

Commander of the Faithful Imam Ali ibn Abi Talib (a.s) said that the Messenger of Allah (swt) (peace and blessings be upon him and his family) said: "Whoever fasts a day voluntarily, Allah (swt), the Almighty, will admit him to Paradise."

Hadith 3

وَ رَوَى جَابِرٌ عَنْ أَبِي جَعْفَرٍ عَلَيْهِ اَلسَّلاَمُ قَالَ: «مَنْ خُتِمَ لَهُ بِصِيَامِ يَوْمٍ دَخَلَ اَلْجَنَّةَ ».

It is narrated by Jabir from Abu Ja‘far (Imam Muhammad ibn Ali Al-Baqir (a.s)), who said: "Whoever's life ends while fasting on a day will enter Paradise."

Hadith 4

وَ قَالَ رَسُولُ اَللَّهِ صَلَّى اَللَّهُ عَلَيْهِ وَ آلِهِ: «مَنْ صَامَ يَوْماً فِي سَبِيلِ اَللَّهِ كَانَ يَعْدِلُ سَنَةً يَصُومُهَا ».

The Messenger of Allah (swt) (peace and blessings be upon him and his family) said: "Whoever fasts a day in the way of Allah (swt), it is equivalent to fasting a whole year."

Hadith 5

وَ قَالَ اَلصَّادِقُ عَلَيْهِ اَلسَّلاَمُ: «مَنْ تَطَيَّبَ بِطِيبٍ أَوَّلَ اَلنَّهَارِ وَ هُوَ صَائِمٌ لَمْ يَفْقِدْ عَقْلَهُ ».

Imam Jafar ibn Muhammad Al-Sadiq (a.s) said: "Whoever applies perfume in the morning while fasting will not lose his mind."

Hadith 6

وَ قَالَ رَسُولُ اَللَّهِ صَلَّى اَللَّهُ عَلَيْهِ وَ آلِهِ: «مَا مِنْ صَائِمٍ يَحْضُرُ قَوْماً يَطْعَمُونَ إِلاَّ سَبَّحَتْ لَهُ أَعْضَاؤُهُ وَ كَانَتْ صَلاَةُ اَلْمَلاَئِكَةِ عَلَيْهِ وَ كَانَتْ صَلاَتُهُمُ اِسْتِغْفَاراً».

The Messenger of Allah (swt) (peace and blessings be upon him and his family) said: "No fasting person sits among a group of people who are eating except, that his limbs will glorify Allah (swt), the angels will send prayers upon him, and their prayers are acts of seeking forgiveness for him."

Hadith 7

وَ رُوِيَ عَنْ مُوسَى بْنِ جَعْفَرٍ عَلَيْهِمَا اَلسَّلاَمُ قَالَ: «مَنْ صَامَ أَوَّلَ يَوْمٍ مِنْ عَشْرِ ذِي اَلْحِجَّةِ كَتَبَ اَللَّهُ لَهُ صَوْمَ ثَمَانِينَ شَهْراً فَإِنْ صَامَ اَلتِّسْعَ كَتَبَ اَللَّهُ عَزَّ وَ جَلَّ لَهُ صَوْمَ اَلدَّهْرِ».

It is narrated from Imam Musa ibn Jafar Al-Kadhim (a.s) who said: "Whoever fasts the first day of the ten days of Dhu al-Hijjah, Allah (swt) will record for him the reward of fasting eighty months. And if he fasts all nine days, Allah (swt), the Almighty, will record for him the reward of fasting a lifetime."

Hadith 8

وَ قَالَ اَلصَّادِقُ عَلَيْهِ اَلسَّلاَمُ: «صَوْمُ يَوْمِ اَلتَّرْوِيَةِ كَفَّارَةُ سَنَةٍ وَ يَوْمِ عَرَفَةَ كَفَّارَةُ سَنَتَيْنِ.

Imam Jafar ibn Muhammad Al-Sadiq (a.s) said: "Fasting on the Day of Tarwiyah is an expiation for one year, and fasting on the Day of Arafah is an expiation for two years."

Hadith 9

وَ رُوِيَ: «أَنَّ فِي أَوَّلِ يَوْمٍ مِنْ ذِي اَلْحِجَّةِ وُلِدَ إِبْرَاهِيمُ خَلِيلُ اَلرَّحْمَنِ عَلَيْهِ اَلسَّلاَمُ فَمَنْ صَامَ ذَلِكَ اَلْيَوْمَ كَانَ كَفَّارَةَ سِتِّينَ سَنَةً وَ فِي تِسْعٍ مِنْ ذِي اَلْحِجَّةِ أُنْزِلَتْ تَوْبَةُ دَاوُدَ عَلَيْهِ اَلسَّلاَمُ فَمَنْ صَامَ ذَلِكَ اَلْيَوْمَ كَانَ كَفَّارَةَ تِسْعِينَ سَنَةً.

It is narrated: "On the first day of Dhu al-Hijjah, Ibrahim, the Friend of the Most Merciful (a.s), was born. Whoever fasts on that day, it will be an expiation for sixty years. On the ninth of Dhu al-Hijjah, the repentance of Dawud (a.s) was accepted. Whoever fasts on that day, it will be an expiation for ninety years."

Hadith 10

وَ رُوِيَ عَنْ يَعْقُوبَ بْنِ شُعَيْبٍ قَالَ: سَأَلْتُ أَبَا عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ عَنْ صَوْمِ يَوْمِ عَرَفَةَ قَالَ «إِنْ شِئْتَ صُمْتَ وَ إِنْ شِئْتَ لَمْ تَصُمْ» وَ ذَكَرَ «أَنَّ رَجُلاً أَتَى اَلْحَسَنَ وَ اَلْحُسَيْنَ عَلَيْهِمَا اَلسَّلاَمُ فَوَجَدَ أَحَدَهُمَا صَائِماً وَ اَلْآخَرَ مُفْطِراً فَسَأَلَهُمَا فَقَالاَ «إِنْ صُمْتَ فَحَسَنٌ وَ إِنْ لَمْ تَصُمْ فَجَائِزٌ».

It is narrated from Ya‘qub ibn Shu‘ayb, who said: I asked Abu Abdullah (Imam Jafar ibn Muhammad Al-Sadiq (a.s)) about fasting on the Day of Arafah. Imam (a.s) said: 'If you wish, you may fast, and if you wish, you may refrain from fasting.' Imam (a.s) mentioned: 'A man came to al-Hasan (a.s) and al-Husayn (a.s) and found one of them fasting and the other not fasting. He asked them, and they said: "If you fast, it is good, and if you do not fast, it is permissible."’"

Hadith 11

وَ رَوَى عَبْدُ اَللَّهِ بْنُ اَلْمُغِيرَةِ عَنْ سَالِمٍ عَنْ أَبِي عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ قَالَ: «أَوْصَى رَسُولُ اَللَّهِ صَلَّى اَللَّهُ عَلَيْهِ وَ آلِهِ إِلَى عَلِيٍّ عَلَيْهِ اَلسَّلاَمُ وَحْدَهُ وَ أَوْصَى عَلِيٌّ عَلَيْهِ اَلسَّلاَمُ إِلَى اَلْحَسَنِ وَ اَلْحُسَيْنِ عَلَيْهِمَا اَلسَّلاَمُ جَمِيعاً وَ كَانَ اَلْحَسَنُ عَلَيْهِ اَلسَّلاَمُ إِمَامَهُ فَدَخَلَ رَجُلٌ يَوْمَ عَرَفَةَ عَلَى اَلْحَسَنِ عَلَيْهِ اَلسَّلاَمُ وَ هُوَ يَتَغَدَّى وَ اَلْحُسَيْنُ عَلَيْهِ اَلسَّلاَمُ صَائِمٌ ثُمَّ جَاءَ بَعْدَ مَا قُبِضَ اَلْحَسَنُ عَلَيْهِ اَلسَّلاَمُ فَدَخَلَ عَلَى اَلْحُسَيْنِ عَلَيْهِ اَلسَّلاَمُ يَوْمَ عَرَفَةَ وَ هُوَ يَتَغَدَّى وَ عَلِيُّ بْنُ اَلْحُسَيْنِ عَلَيْهِمَا اَلسَّلاَمُ صَائِمٌ فَقَالَ لَهُ اَلرَّجُلُ إِنِّي دَخَلْتُ عَلَى اَلْحَسَنِ عَلَيْهِ اَلسَّلاَمُ وَ هُوَ يَتَغَدَّى وَ أَنْتَ صَائِمٌ ثُمَّ دَخَلْتُ عَلَيْكَ وَ أَنْتَ مُفْطِرٌ فَقَالَ «إِنَّ اَلْحَسَنَ عَلَيْهِ اَلسَّلاَمُ كَانَ إِمَاماً فَأَفْطَرَ لِئَلاَّ يُتَّخَذَ صَوْمُهُ سُنَّةً وَ لِيَتَأَسَّى بِهِ اَلنَّاسُ فَلَمَّا أَنْ قُبِضَ كُنْتُ أَنَا اَلْإِمَامَ فَأَرَدْتُ أَنْ لاَ يُتَّخَذَ صَوْمِي سُنَّةً فَيَتَأَسَّى اَلنَّاسُ بِي».

It is narrated by Abdullah ibn al-Mughira from Salim, from Abu Abdullah (Imam Jafar ibn Muhammad Al-Sadiq (a.s)), who said: "The Messenger of Allah (swt) (peace and blessings be upon him and his family) bequeathed solely to Ali (a.s), and Ali (a.s) bequeathed jointly to al-Hasan (a.s) and al-Husayn (a.s). Al-Hasan (a.s) was the Imam during his time. A man entered upon al-Hasan (a.s) on the Day of Arafah and found him having lunch, while al-Husayn (a.s) was fasting. After al-Hasan (a.s) passed away, the same man entered upon al-Husayn (a.s) on the Day of Arafah and found him having lunch, while Ali ibn al-Husayn (a.s) was fasting. The man said to Imam: 'I came to al-Hasan (a.s) when he was having lunch, and you were fasting. Then I came to you, and now you are not fasting.' Imam (a.s) replied: 'Al-Hasan (a.s) was the Imam, so he broke his fast to ensure his fasting would not be taken as a Sunnah and followed by others. When he passed away, I became the Imam, and I did not want my fasting to be taken as a Sunnah and followed by others.'"

Hadith 12

وَ رَوَى حَنَانُ بْنُ سَدِيرٍ عَنْ أَبِيهِ قَالَ: سَأَلْتُهُ عَنْ صَوْمِ يَوْمِ عَرَفَةَ فَقُلْتُ جُعِلْتُ فِدَاكَ إِنَّهُمْ يَزْعُمُونَ أَنَّهُ يَعْدِلُ صَوْمَ سَنَةٍ قَالَ «كَانَ أَبِي عَلَيْهِ اَلسَّلاَمُ لاَ يَصُومُهُ» قُلْتُ وَ لِمَ جُعِلْتُ فِدَاكَ قَالَ « يَوْمُ عَرَفَةَ يَوْمُ دُعَاءٍ وَ مَسْأَلَةٍ فَأَتَخَوَّفُ أَنْ يُضْعِفَنِي عَنِ اَلدُّعَاءِ وَ أَكْرَهُ أَنْ أَصُومَهُ وَ أَتَخَوَّفُ أَنْ يَكُونَ يَوْمُ عَرَفَةَ يَوْمَ اَلْأَضْحَى وَ لَيْسَ بِيَوْمِ صَوْمٍ.

It is narrated by Hanan ibn Sudayr from his father, who said: "I asked him about fasting on the Day of Arafah, and I said: 'May I be your ransom, they claim that fasting it equals fasting for a year.' Imam (a.s) said: 'My father (a.s) would not fast on that day.' I asked: 'Why? May I be your ransom.' Imam (a.s) said: 'The Day of Arafah is a day of supplication and asking (from Allah (swt)). I fear that fasting might weaken me from making supplications, and I dislike fasting it as I fear that the Day of Arafah may coincide with the Day of Eid al-Adha, which is not a day of fasting.'"

Commentary 1

قال مصنف هذا الكتاب - رحمه الله -: إن العامة غير موفقين لفطر ولا أضحى و إنما كره عليه السلام صوم يوم عرفة لأنه كان يكون يوم العيد في أكثر السنين و تصديق ذلك:

The compiler of this book - may Allah (swt) have mercy on him, said: "The general populace lacks understanding about fasting and Eid. Imam (a.s) disliked fasting on the Day of Arafah because it often coincided with the Day of Eid in many years. The confirmation of this is evident."

Hadith 13

مَا قَالَهُ اَلصَّادِقُ عَلَيْهِ اَلسَّلاَمُ: «لَمَّا قُتِلَ اَلْحُسَيْنُ بْنُ عَلِيٍّ عَلَيْهِ اَلسَّلاَمُ أَمَرَ اَللَّهُ عَزَّ وَ جَلَّ مَلَكاً فَنَادَى أَيَّتُهَا اَلْأُمَّةُ اَلظَّالِمَةُ اَلْقَاتِلَةُ عِتْرَةَ نَبِيِّهَا لاَ وَفَّقَكُمُ اَللَّهُ تَعَالَى لِصَوْمٍ وَ لاَ فِطْرٍ ».

Imam Jafar ibn Muhammad Al-Sadiq (a.s) said: "When al-Husayn ibn Ali (a.s) was martyred, Allah (swt), the Almighty, commanded an angel to proclaim: 'O oppressive nation, O killers of the progeny of your Prophet (saws), may Allah (swt) not grant you success in fasting or breaking your fast.'"

Hadith 14

وَ فِي حَدِيثٍ آخَرَ: «لاَ وَفَّقَكُمُ اَللَّهُ لِفِطْرٍ وَ لاَ أَضْحًى.

In another narration: "May Allah (swt) not grant you success for Eid al-Fitr or Eid al-Adha."

Commentary 2

ومن صام يوم عرفة فله من الثواب ما ذكرناه.

And whoever fasts on the Day of Arafah will receive the reward that has been mentioned earlier.

Hadith 15

وَ رُوِيَ عَنِ اَلْحَسَنِ بْنِ عَلِيٍّ اَلْوَشَّاءِ قَالَ: كُنْتُ مَعَ أَبِي وَ أَنَا غُلاَمٌ فَتَعَشَّيْنَا عِنْدَ اَلرِّضَا عَلَيْهِ اَلسَّلاَمُ لَيْلَةَ خَمْسَةٍ وَ عِشْرِينَ مِنْ ذِي اَلْقَعْدَةِ فَقَالَ لَهُ « لَيْلَةُ خَمْسَةٍ وَ عِشْرِينَ مِنْ ذِي اَلْقَعْدَةِ وُلِدَ فِيهَا إِبْرَاهِيمُ عَلَيْهِ اَلسَّلاَمُ وَ وُلِدَ فِيهَا عِيسَى اِبْنُ مَرْيَمَ عَلَيْهِ اَلسَّلاَمُ وَ فِيهَا دُحِيَتِ اَلْأَرْضُ مِنْ تَحْتِ اَلْكَعْبَةِ فَمَنْ صَامَ ذَلِكَ اَلْيَوْمَ كَانَ كَمَنْ صَامَ سِتِّينَ شَهْراً».

It is narrated from al-Hasan ibn Ali al-Washa, who said: ‘I was with my father when I was a boy, and we had dinner with Imam Ali ibn Musa Ar-Ridha (a.s) on the night of the 25th of Dhu al-Qa‘dah.’ Imam (a.s) said to him: 'The 25th night of Dhu al-Qa‘dah is the night on which Ibrahim (a.s) was born, and on which Isa ibn Maryam (a.s) was born, and it is the night when the earth was spread out from beneath the Ka‘bah. Whoever fasts on that day, it is as if he has fasted for sixty months.'"

Hadith 16

وَ رُوِيَ: «أَنَّ فِي تِسْعٍ وَ عِشْرِينَ مِنْ ذِي اَلْقَعْدَةِ أَنْزَلَ اَللَّهُ عَزَّ وَ جَلَّ اَلْكَعْبَةَ وَ هِيَ أَوَّلُ رَحْمَةٍ نَزَلَتْ فَمَنْ صَامَ ذَلِكَ اَلْيَوْمَ كَانَ كَفَّارَةَ سَبْعِينَ سَنَةً ».

It is narrated: "On the 29th of Dhu al-Qa‘dah, Allah (swt), the Almighty, sent down the Ka‘bah, which was the first mercy to descend. Whoever fasts on that day, it will be an expiation for seventy years."

Hadith 17

وَ رَوَى اَلْحَسَنُ بْنُ رَاشِدٍ عَنْ أَبِي عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ قَالَ: قُلْتُ جُعِلْتُ فِدَاكَ، لِلْمُسْلِمِينَ عِيدٌ غَيْرُ اَلْعِيدَيْنِ قَالَ «نَعَمْ يَا حَسَنُ وَ أَعْظَمُهُمَا وَ أَشْرَفُهُمَا» قَالَ قُلْتُ لَهُ فَأَيُّ يَوْمٍ هُوَ قَالَ «هُوَ يَوْمٌ نُصِبَ أَمِيرُ اَلْمُؤْمِنِينَ عَلَيْهِ اَلسَّلاَمُ عَلَماً لِلنَّاسِ» قُلْتُ جُعِلْتُ فِدَاكَ وَ أَيُّ يَوْمٍ هُوَ قَالَ «إِنَّ اَلْأَيَّامَ تَدُورُ وَ هُوَ يَوْمُ ثَمَانِيَةَ عَشَرَ مِنْ ذِي اَلْحِجَّةِ » قَالَ قُلْتُ جُعِلْتُ فِدَاكَ وَ مَا يَنْبَغِي لَنَا أَنْ نَصْنَعَ فِيهِ قَالَ «تَصُومُهُ يَا حَسَنُ وَ تُكْثِرُ فِيهِ اَلصَّلاَةَ عَلَى مُحَمَّدٍ وَ أَهْلِ بَيْتِهِ عَلَيْهِمُ اَلسَّلاَمُ وَ تَبَرَّأُ إِلَى اَللَّهِ عَزَّ وَ جَلَّ مِمَّنْ ظَلَمَهُمْ حَقَّهُمْ فَإِنَّ اَلْأَنْبِيَاءَ عَلَيْهِمُ اَلسَّلاَمُ كَانَتْ تَأْمُرُ اَلْأَوْصِيَاءَ بِالْيَوْمِ اَلَّذِي كَانَ يُقَامُ فِيهِ اَلْوَصِيُّ أَنْ يُتَّخَذَ عِيداً» قَالَ قُلْتُ مَا لِمَنْ صَامَهُ مِنَّا قَالَ «صِيَامُ سِتِّينَ شَهْراً وَ لاَ تَدَعْ صِيَامَ يَوْمِ سَبْعَةٍ وَ عِشْرِينَ مِنْ رَجَبٍ فَإِنَّهُ هُوَ اَلْيَوْمُ اَلَّذِي أُنْزِلَتْ فِيهِ اَلنُّبُوَّةُ عَلَى مُحَمَّدٍ صَلَّى اَللَّهُ عَلَيْهِ وَ آلِهِ وَ ثَوَابُهُ مِثْلُ سِتِّينَ شَهْراً لَكُمْ.

It is narrated by al-Hasan ibn Rashid from Abu Abdullah (Imam Jafar ibn Muhammad Al-Sadiq (a.s)), who said: I said: 'May I be your ransom, is there a festival for Muslims other than the two Eids?' Imam (a.s) said: 'Yes, O’ Hasan, and it is greater and more noble than them.' I said: 'What day is it?' Imam (a.s) said: 'It is the day on which Amir al-Mu'minin (a.s) was appointed as a guide for the people.' I said: 'May I be your ransom, which day is that?' Imam (a.s) said: 'The days revolve, and it is the 18th of Dhu al-Hijjah.' I said: 'May I be your ransom, what should we do on that day?' Imam (a.s) said: 'You should fast it, O’ Hasan, and increase your prayers upon Muhammad and his family (a.s). You should also declare your disassociation to Allah (swt), the Almighty, from those who wronged them and usurped their rights. Indeed, the Prophets (a.s) used to command their successors to designate the day on which the successor was appointed as a festival.' I said: 'What is the reward for fasting it for us?' Imam (a.s) said: 'The reward of fasting sixty months. Also, do not neglect fasting on the 27th of Rajab, for it is the day on which prophethood was bestowed upon Muhammad (saws) (peace and blessings be upon him and his family), and its reward for you is like fasting sixty months.'"

Hadith 18

وَ رَوَى اَلْمُفَضَّلُ بْنُ عُمَرَ عَنْ أَبِي عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ قَالَ: «صَوْمُ يَوْمِ غَدِيرِ خُمٍّ كَفَّارَةُ سِتِّينَ سَنَةً.

It is narrated by al-Mufaddal ibn Umar from Abu Abdullah (Imam Jafar ibn Muhammad Al-Sadiq (a.s)), who said: "Fasting on the Day of Ghadir Khumm is an expiation for sixty years."

Commentary 3

وأما خبر صلاة يوم غدير خم والثواب المذكور فيه لمن صامه فإن شيخنا محمد ابن الحسن - رضي الله عنه - كان لا يصححه ويقول: إنه من طريق محمد بن موسى الهمداني وكان كذابا غير ثقة وكل ما لم يصححه ذلك الشيخ - قدس الله روحه - ولم يحكم بصحته من الاخبار فهو عندنا متروك غير صحيح.

As for the report regarding the prayer on the Day of Ghadir Khumm and the reward mentioned for fasting it, our Sheikh Muhammad ibn al-Hasan (may Allah (swt) be pleased with him) did not authenticate it. He stated that it comes through Muhammad ibn Musa al-Hamdani, who was a liar and untrustworthy. Any report that our Sheikh (may Allah (swt) sanctify his soul) did not authenticate or deem correct is, in our view, to be discarded and considered unreliable.

Hadith 19

وَ فِي أَوَّلِ يَوْمٍ مِنَ اَلْمُحَرَّمِ دَعَا زَكَرِيَّا عَلَيْهِ اَلسَّلاَمُ رَبَّهُ عَزَّ وَ جَلَّ فَمَنْ صَامَ ذَلِكَ اَلْيَوْمَ اِسْتَجَابَ اَللَّهُ لَهُ كَمَا اِسْتَجَابَ لِزَكَرِيَّا عَلَيْهِ اَلسَّلاَمُ ».

It is narrated: "On the first day of Muharram, Zakariya (a.s) supplicated to his Lord (azj), the Almighty. Whoever fasts on that day, Allah (swt) will answer their supplication just as He answered Zakariya (a.s)."

Hadith 20

وَ سَأَلَ أَبُو بَصِيرٍ أَبَا عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ: عَنِ اَلصَّائِمِ اَلْمُتَطَوِّعِ تَعْرِضُ لَهُ اَلْحَاجَةُ قَالَ «هُوَ بِالْخِيَارِ مَا بَيْنَهُ وَ بَيْنَ اَلْعَصْرِ وَ إِنْ مَكَثَ حَتَّى اَلْعَصْرِ ثُمَّ بَدَأَ لَهُ أَنْ يَصُومَ وَ لَمْ يَكُنْ نَوَى ذَلِكَ فَلَهُ أَنْ يَصُومَ ذَلِكَ اَلْيَوْمَ إِنْ شَاءَ.

Abu Basir asked Abu Abdullah (Imam Jafar ibn Muhammad Al-Sadiq (a.s)) about a person observing an optional fast who encounters a need to break it. Imam (a.s) said: "He has the choice until the time of Asr. If he waits until Asr and then decides to fast without having made the intention earlier, he may still fast that day if he wishes."