✅ Answer: For a traveler who performs a full prayer, three scenarios are possible:

1️⃣ If they prayed a full prayer out of forgetfulness:

1⃣عَنْ أَبِي بصِير عَن أَبِي عَبْداللَّه قَالَ: سَأَلْتُهُ عَنِ الرَّجُلِ يَنْسَى فَيُصَلِّي فِي السَّفَرِ أَرْبَعَ رَكَعَاتٍ قَال إِنْ ذَكَرَ فِي ذَلِكَ الْيَوْمِ فَلْيُعِدْ وَ إِنْ لَمْ يَذْكُرْ حَتَّى يَمْضِيَ ذَلِكَ الْيَوْمُ فَلَا إِعَادَةَ عَلَيْه

📚 *Al-Faqih*, Vol. 1, p. 438

Abu Basir narrated: I asked Imam Sadiq (peace be upon him) about someone who forgets and prays four rak‘ahs while traveling. The Imam said: If they remember on the same day, they must repeat the prayer. If they do not remember until the day has passed, they do not need to repeat it.

2⃣عَن الْعِيص بْن الْقَاسِم قَالَ: سَأَلْتُ أَبا عَبْداللَّهِ عَنْ رَجُلٍ صَلَّى و هُوَ مُسَافِرٌ فَأَتَمَّ الصَّلَاةَ قَالَ إِنْ كَانَ فِي وَقْتٍ فَلْيُعِدْ وَ إِنْ كَانَ الْوَقْتُ قَدْ مَضَى فَلَا

📚 *Al-Kafi*, Vol. 3, p. 435

Ays ibn Qasim narrated: I asked Imam Sadiq (peace be upon him) about a traveler who prayed a full prayer. The Imam said: If it is still within the prayer time, they must repeat it; otherwise, they do not need to.

2️⃣ If the traveler prayed a full prayer out of ignorance, or someone intended a short stay (less than ten days) but prayed a full prayer out of ignorance:

3⃣مَنْصور بْن حَازِم عَن أَبِي عَبْداللَّه قال سَمِعْتُهُ يَقُولُ إِذَا أَتَيْتَ بَلْدَةً فَأَزْمَعْتَ الْمُقَامَ عَشَرَةَ أَيَّامٍ فَأَتِمَّ الصَّلَاة فَإِنْ تَرَكَهُ رَجُلٌ جَاهِلًا فَلَيْسَ عَلَيْهِ إِعَادَةٌ

📚 *Tahdhib*, Vol. 3, p. 221

Mansur ibn Hazim narrated: I heard Imam Sadiq (peace be upon him) say: If you enter a city intending to stay for ten days, pray a full prayer. But if someone neglects this out of ignorance, they do not need to repeat the prayer.

4⃣عَن زُرَارَة و مُحَمَّدبْن مُسْلِمٍ قَالا قُلْنَا لِأَبِي جَعْفَر رَجُلٌ صَلَّى فِي السَّفَرِ أَرْبَعاً أَيُعِيدُ أَمْ لَا قَالَ إِنْ كَانَ قُرِئَتْ عَلَيْهِ آيَةُ التَّقْصِيرِ وَ فُسِّرَتْ لَهُ فَصَلَّى أَرْبَعاً أَعَادَ و إِنْ لَمْ يَكُنْ قُرِئَتْ عَلَيْهِ وَ لَمْ يَعْلَمْهَا فَلَا إِعَادَةَ عَلَيْه

📚 *Al-Faqih*, Vol. 1, p. 435

Zurarah and Muhammad ibn Muslim narrated: We asked Imam Baqir (peace be upon him): If a traveler prays four rak‘ahs, should they repeat it? He said: If the verse about shortening the prayer and its explanation were conveyed to them, but they still prayed four rak‘ahs, they must repeat it. However, if the verse was not conveyed to them, and they were unaware, they do not need to repeat it.

3️⃣ If the traveler intentionally prayed a full prayer:

5⃣ عن جَعْفَربْنِ مُحَمَّد فِي حَدِيثِ شَرَائِع الدِّين قَال: وَ التَّقْصِيرُ فِي ثَمَانِيَةِ فَرَاسِخَ وَ هُوَ بَرِيدَانِ وَ إِذَا قَصَّرْتَ أَفْطَرْتَ وَ مَنْ لَمْ يُقَصِّرْ فِي السَّفَرِ لَمْ تُجْزِ صَلَاتُهُ لِأَنَّهُ قَدْ زَادَ فِي فَرْضِ اللَّهِ عَزَّ وَ جَلَّ

📚 *Al-Khisal*, p. 604, Hadith 9

Imam Sadiq (peace be upon him) said: Shortening the prayer is obligatory at a distance of eight farsakhs (two barids). If you shorten the prayer, you also break your fast. If someone does not shorten their prayer while traveling, their prayer is invalid because they have added two rak‘ahs to the divine obligation.

6⃣الْحَلَبِيِّ قَالَ: قُلْتُ لِأَبِي عَبْدِ اللَّه صَلَّيْتُ الظُّهْرَ أَرْبَعَ رَكَعَاتٍ وَ أَنَا فِي سَفَرٍ قَالَ أَعِدْ

📚 *Tahdhib*, Vol. 2, p. 14

Halabi narrated: I told Imam Sadiq (peace be upon him): I prayed four rak‘ahs for Dhuhr while traveling. The Imam said: Repeat your prayer!

✅ Ruling for a traveler who must break their fast but still fasts while traveling:

7⃣الْحَلَبِيّ قَالَ: قُلْتُ لِأَبِي عَبْداللَّه رَجُلٌ صَامَ فِي السَّفَرِ فَقَالَ إِنْ كَانَ بَلَغَهُ أَنَّ رَسُولَ اللَّهِ نَهَى عَنْ ذَلِكَ فَعَلَيْهِ الْقَضَاءُ وَ إِنْ لَمْ يَكُنْ بَلَغَهُ فَلَا شَيْ ءَ عَلَيْه

📚 *Tahdhib*, Vol. 4, p. 221

Halabi narrated: I asked Imam Sadiq (peace be upon him): What is the ruling for someone who fasts while traveling? He said: If they know that the Messenger of Allah (peace be upon him and his family) prohibited this, they must make up the fast. If they do not know, there is nothing upon them.

📚 *Al-Kafi*, Vol. 4, p. 128

Imam Sadiq (peace be upon him) said: When someone travels during Ramadan, they must break their fast. If they fast out of ignorance, they do not need to make it up.