✅Answer: Please pay attention to the following narrations:

1 عَنْ عَبْدِ اللَّهِ بْنِ مَيْمُونٍ عَنْ أَبِي عَبْدِ اللَّهِ عن أبیه قَالَ: ثَلَاثَةٌ لَا يُفَطِّرْنَ الصَّائِمَ الْقَيْ ءُ وَ الِاحْتِلَامُ وَ الْحِجَامَةُ الْحَدِيثَ.

📚 Al-Tahdhib, Vol. 4, p. 260

📚 Al-Istibsar, Vol. 2, p. 90

Abu Abdullah, Imam Sadiq (peace be upon him) said:

Three things do not break the fast of the one who is fasting: (unintentional) vomiting, nocturnal emission (becoming ritually impure in one's sleep), and cupping (hijamah)...

2 عَنِ ابْنِ بُكَيْرٍ فِي حَدِيثٍ قَالَ: سَأَلْتُ أَبَا عَبْدِ اللَّهِ عَنِ الرَّجُلِ يَحْتَلِمُ بِالنَّهَارِ فِي شَهْرِ رَمَضَانَ يُتِمُّ صَوْمَهُ كَمَا هُوَ فَقَالَ لَا بَأْسَ.

📚 Al-Kafi, Vol. 4, p. 105

Ibn Bukayr said: I asked Imam Sadiq (peace be upon him) about a man who has a nocturnal emission during the day in the month of Ramadan and completes his fast as it was. He said: There is no problem.

3 عَنْ عُمَرَ بْنِ يَزِيدَ قَالَ: قُلْتُ لِأَبِي عَبْدِ اللَّهِ لِأَيِّ عِلَّةٍ لَا يُفَطِّرُ الِاحْتِلَامُ الصَّائِمَ وَ النِّكَاحُ يُفَطِّرُ الصَّائِمَ قَالَ لِأَنَّ النِّكَاحَ فِعْلُهُ وَ الِاحْتِلَامَ مَفْعُولٌ بِهِ.

📚 Ilal al-Shara'i, p. 379

Umar ibn Yazid said: I said to Abu Abdullah, Imam Sadiq (peace be upon him): For what reason does nocturnal emission not break the fast of the one who is fasting, but sexual intercourse breaks the fast? He said: Because sexual intercourse is his own action and doing, but nocturnal emission happens to him (it is involuntary).

4 عَنْ إِبْرَاهِيمَ بْنِ عَبْدِ الْحَمِيدِ عَنْ بَعْضِ مَوَالِيهِ قَالَ سَأَلْتُهُ عَنِ احْتِلَامِ الصَّائِمِ قَالَ فَقَالَ إِذَا احْتَلَمَ نَهَاراً فِي شَهْرِ رَمَضَانَ فَلَا يَنَمْ حَتَّى يَغْتَسِلَ...

📚 Al-Tahdhib, Vol. 4, p. 320

A person said: I asked him (the Imam, peace be upon him) about the nocturnal emission of a person who is fasting. He said: When he has a nocturnal emission during the day in the month of Ramadan, he should not sleep until he performs ghusl.

5 عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ قَالَ سَمِعْتُ أَبَا جَعْفَرٍ يَقُولُ لَا يَضُرُّ الصَّائِمَ مَا صَنَعَ إِذَا اجْتَنَبَ ثَلَاثَ خِصَالٍ الطَّعَامَ وَ الشَّرَابَ وَ النِّسَاءَ وَ الِارْتِمَاسَ فِي الْمَاءِ.

📚 Al-Tahdhib, Vol. 4, p. 189

Muhammad ibn Muslim said: I heard Abu Ja'far, Imam Baqir (peace be upon him) say: What the one who is fasting does does not harm him as long as he avoids three things: eating and drinking, women, and immersing oneself in water.

6 عَنْ أَحْمَدَ بْنِ أَبِي عَبْدِ اللَّهِ عَنْ أَبِيهِ رَفَعَهُ إِلَى أَبِي عَبْدِ اللَّهِ قَالَ: خَمْسَةُ أَشْيَاءَ تُفَطِّرُ الصَّائِمَ الْأَكْلُ وَ الشُّرْبُ وَ الْجِمَاعُ وَ الِارْتِمَاسُ فِي الْمَاءِ وَ الْكَذِبُ عَلَى اللَّهِ وَ عَلَى رَسُولِهِ وَ عَلَى الْأَئِمَّةِ

📚 Al-Khisal, p. 286, hadith 39

Abu Abdullah, Imam Sadiq (peace be upon him) said:

Five things break the fast of the one who is fasting: eating and drinking, sexual intercourse, immersing oneself in water, and lying about Allah, His Messenger, and the Imams (peace be upon them).

7 عَنِ الْعِيصِ بْنِ الْقَاسِمِ أَنَّهُ سَأَلَ أَبَا عَبْدِ اللَّهِ عَنِ الرَّجُلِ يَنَامُ فِي شَهْرِ رَمَضَانَ- فَيَحْتَلِمُ ثُمَّ يَسْتَيْقِظُ ثُمَّ يَنَامُ قَبْلَ أَنْ يَغْتَسِلَ قَالَ لَا بَأْسَ

📚 Al-Faqih, Vol. 2, p. 120

Is ibn Qasim asked Abu Abdullah, Imam Sadiq (peace be upon him) about a person who sleeps during the month of Ramadan and has a nocturnal emission, then wakes up and sleeps again before performing ghusl. He said: There is no problem.

✅It is clear from the above narrations that nocturnal emission during the day does not invalidate any fast. However, in the month of Ramadan, it has been instructed that in case of nocturnal emission during the day, one should not sleep until he performs ghusl, although in hadith 7, a concession for sleeping before ghusl has also been mentioned.