✅Answer: Please pay attention to the following narrations:

1 الْكَاهِلِيِّ قَالَ: سَأَلْتُ أَبَا عَبْدِ اللَّهِ عَنِ الْيَوْمِ الَّذِي يُشَكُّ فِيهِ مِنْ شَعْبَانَ- قَالَ لَأَنْ أَصُومَ يَوْماً مِنْ شَعْبَانَ- أَحَبُّ إِلَيَّ مِنْ أَنْ أُفْطِرَ يَوْماً مِنْ شَهْرِ رَمَضَانَ

📚 Al-Kafi, vol. 4, p. 81

Kahili said: 'I asked Imam Sadiq, peace be upon him, about the day of the month of Sha'ban that falls into doubt (that it might be from the month of Ramadan).' The Imam said: 'If I were to fast one day of the month of Sha'ban, it would be more beloved to me than to break my fast on one day of the month of Ramadan.'

2 سَعِيدٍ الْأَعْرَج قَالَ: قُلْتُ لِأَبِي عَبْدِ اللَّهِ إِنِّي صُمْتُ الْيَوْمَ الَّذِي يُشَكُّ فِيهِ فَكَانَ مِنْ شَهْرِ رَمَضَانَ أَفَأَقْضِيهِ قَالَ لَا هُوَ يَوْمٌ وُفِّقْتَ لَهُ

📚 Al-Kafi, vol. 4, p. 82

A'raj said: 'I said to Imam Sadiq, peace be upon him: 'I fasted the Day of Doubt, and (later I realized) that it was from the month of Ramadan. Should I make it up?' He said: 'No, that was a day you were successful in.'

3 بَشِيرٍ النَّبَّال عَنْ أَبِي عَبْدِ اللَّهِ قَالَ: سَأَلْتُهُ عَنْ صَوْمِ يَوْمِ الشَّكِّ فَقَالَ صُمْهُ فَإِنْ يَكُ مِنْ شَعْبَانَ كَانَ تَطَوُّعاً وَ إِنْ يَكُ مِنْ شَهْرِ رَمَضَانَ فَيَوْمٌ وُفِّقْتَ لَهُ

📚 Al-Kafi, vol. 4, p. 82

Bashir said: 'I asked Imam Sadiq, peace be upon him, about fasting the Day of Doubt.' The Imam said: 'Fast it, for if it is from Sha'ban, it is considered a supererogatory prayer, and if it is from Ramadan, it is a day you were successful in.'

4 عَنْ سَمَاعَةَ قَالَ: سَأَلْتُهُ عَنِ الْيَوْمِ الَّذِي يُشَكُّ فِيهِ مِنْ شَهْرِ رَمَضَانَ- لَا يَدْرِي أَهُوَ مِنْ شَعْبَانَ أَوْ مِنْ شَهْرِ رَمَضَانَ- فَصَامَهُ فَكَانَ مِنْ شَهْرِ رَمَضَانَ- قَالَ هُوَ يَوْمٌ وُفِّقَ لَهُ لَا قَضَاءَ عَلَيْهِ

📚 Al-Kafi, vol. 4, p. 81

Sama'ah said: 'I asked the Imam about a day of Ramadan that is doubtful and a person does not know if it is from the month of Sha'ban or from the month of Ramadan and he fasts it, and (later it becomes clear that) it was from the month of Ramadan.' The Imam said: 'It is a day that he was successful in, and there is no make-up on him.'

5 عَنْ أَبِي جَعْفَرٍ فِي الرَّجُلِ يَصُومُ الْيَوْمَ الَّذِي يُشَكُّ فِيهِ مِنْ رَمَضَانَ- فَقَالَ عَلَيْهِ قَضَاؤُهُ وَ إِنْ كَانَ كَذَلِكَ

📚 Al-Tahdheeb, vol. 4, p. 182

Imam Baqir, peace be upon him, said about a person who fasts the Day of Doubt as part of Ramadan: 'The make-up of it is on him, even if it was from the month of Ramadan!'

6 مُحَمَّدِ بْن شِهَابٍ الزُّهْرِيِّ قَالَ سَمِعْتُ عَلِيَّ بْنَ الْحُسَيْنِ يَقُولُ يَوْمُ الشَّكِّ أَمَرْنَا بِصِيَامِهِ وَ نَهَيْنَا عَنْهُ أَمَرْنَا أَنْ يَصُومَهُ الْإِنْسَانُ عَلَى أَنَّهُ مِنْ شَعْبَانَ- وَ نَهَيْنَا عَنْ أَنْ يَصُومَهُ عَلَى أَنَّهُ مِنْ شَهْرِ رَمَضَانَ وَ هُوَ لَمْ يَرَ الْهِلَالَ

📚 Al-Tahdheeb, vol. 7, p. [page number missing in original]

Zuhri said: 'I heard Imam Sajjad, peace be upon him, say: 'We both prohibit and command fasting the Day of Doubt! We command a person to fast it as part of the month of Sha'ban, and we prohibit him from fasting it as part of the month of Ramadan, while he has not sighted the crescent of the month (of Ramadan).'

7 عَنْ أَبِي جَعْفَرٍ فِي حَدِيثٍ قَالَ: قَالَ رَسُولُ اللَّهِ مَنْ أَلْحَقَ فِي رَمَضَانَ يَوْماً مِنْ غَيْرِهِ متعمدا فَلَيْسَ بِمُؤْمِنٍ بِاللَّهِ وَ لَا بِي

📚 Al-Tahdheeb, vol. 4, p. 161

Imam Baqir, peace be upon him, said: 'The Messenger of Allah, peace be upon him and his family, said in a hadith: 'Whoever intentionally adds a day from another month to the month of Ramadan does not believe in Allah and in me.'

✅ From the above narrations, it is clear that the 'Day of Doubt' is the 30th day of the month of Sha'ban, which sometimes, due to obstacles in the sky and so on, becomes uncertain whether it is the 30th of Sha'ban or the 1st of Ramadan.

In such a situation, we are obligated to fast it as the last day of Sha'ban, and if it is later found out that it was the first of Ramadan, it suffices for us and there is no need for a make-up. And if someone fasts the Day of Doubt as part of Ramadan without the beginning of the month being proven through legitimate channels, in addition to being severely condemned in hadith 7 and others, even though he has fasted it, he must make it up according to hadith 5.

✅ By contemplating the very narrations of the Ahl al-Bayt, peace be upon them, we can take knowledge from its pure and clean source and build our actions upon it, so that in addition to fulfilling our duty, we can benefit from the indescribable pleasure of acting upon the luminous texts of the hadiths of the Ahl al-Bayt, God willing.

اللَّهُمَّ صَلِّ عَلَی مُحَمَّدٍ وَ آلِ مُحَمَّدٍ

وَ عَجِّلْ لِوَلِیِّکَ الْفَرَجَ وَ الْعَافِیَةَ وَ النَّصْرَ