✅ Answer: Please refer to the following narrations:

1⃣عَنْ أَبِی مُحَمَّدٍ هَارُونَ بْنِ مُوسَی عَنْ مُحَمَّدِ بْنِ عَلِیِّ بْنِ مَعْمَرٍ عَنْ مُحَمَّدِ بْنِ الْحُسَیْنِ بْنِ أَبِی الْخَطَّابِ عَنْ مُحَمَّدِ بْنِ سِنَانٍ عَنِ الْمُفَضَّلِ بْنِ عُمَرَ عَنْ أَبِی عَبْدِ اللَّهِ أَنَّهُ قَالَ : تُصَلِّی فِی شَهْرِ رَمَضَانَ زِیَادَةَ أَلْفِ رَکْعَةٍ... إلی أَنْ قَالَ : ثُمَّ قَالَ یَا مُفَضَّلَ بْنَ عُمَرَ تَقْرَأُ فِی هَذِهِ الصَّلَوَاتِ کُلِّهَا أَعْنِی صَلَاةَ شَهْرِ رَمَضَانَ الزِّیَادَةَ مِنْهَا بِالْحَمْدِ وَ قُلْ هُوَ اللَّهُ أَحَدٌ إِنْ شِئْتَ مَرَّةً وَ إِنْ شِئْتَ ثَلَاثاً وَ إِنْ شِئْتَ خَمْساً وَ إِنْ شِئْتَ سَبْعاً وَ إِنْ شِئْتَ عَشْراً

📚 Al-Tahdhib, vol. 3, p. 66

Mufaddal ibn Umar said: Imam Sadiq, peace be upon him, said: In the month of Ramadan, you pray a thousand extra rak'ahs.... until he said: Then Imam Sadiq, peace be upon him, said: O Mufaddal ibn Umar! In all of these prayers, that is, the extra prayers of Ramadan, recite Surah Al-Fatiha (once) and Surah Al-Ikhlas, if you want, once, and if you want, three times, and if you want, five times, and if you want, seven times, and if you want, ten times.

2⃣عَنْ سَعْدَانَ بْنِ مُسْلِمٍ عَنْ أَبِی بَصِیرٍ قَالَ: قَالَ أَبُو عَبْدِ اللَّهِ صَلِّ فِی الْعِشْرِینَ مِنْ شَهْرِ رَمَضَانَ ثَمَانِیاً بَعْدَ الْمَغْرِبِ وَ اثْنَتَیْ عَشْرَةَ رَکْعَةً بَعْدَ الْعَتَمَةِ فَإِذَا کَانَتِ اللَّیْلَةُ الَّتِی یُرْجَی فِیهَا مَا یُرْجَی فَصَلِّ مِائَةَ رَکْعَةٍ تَقْرَأُ فِی کُلِّ رَکْعَةٍ قُلْ هُوَ اللَّهُ أَحَدٌ عَشْرَ مَرَّاتٍ قَالَ قُلْتُ جُعِلْتُ فِدَاکَ فَإِنْ لَمْ أَقْوَ قَائِماً قَالَ فَجَالِساً قُلْتُ فَإِنْ لَمْ أَقْوَ جَالِساً قَالَ فَصَلِّ وَ أَنْتَ مُسْتَلْقٍ عَلَی فِرَاشِکَ.

📚 Al-Tahdhib, vol. 3, p. 64

Imam Sadiq, peace be upon him, said: In the first twenty nights of Ramadan, read eight rak'ahs after Maghrib and twelve rak'ahs after Isha. Then, on the night when hope is expected for reaching Laylat al-Qadr, pray one hundred rak'ahs, reciting Surah Al-Ikhlas ten times in each rak'ah! I said: May I be sacrificed for you! What if I don't have the strength to stand? He replied: Then pray sitting! I said: What if I don't have the strength to sit? He replied: Then pray while lying on your back in your bed!

✅ Refer to the following link as well:

https://t.me/porseshvapasokhe/683

✅ Based on the above narrations and others, in the additional Nafl prayers performed in Ramadan, after Surah Al-Fatiha, it is recommended that in each rak'ah, Surah Al-Ikhlas be recited either ten times, seven times, five times, three times, or once.

اللَّهُمَّ صَلِّ عَلَی مُحَمَّدٍ وَ آلِ مُحَمَّدٍ وَ عَجِّلْ لِوَلِیِّکَ الْفَرَجَ وَ الْعَافِیَةَ وَ النَّصْر