✅Answer: Please pay attention to the following narrations:

1 عَنْ زُرَارَةَ قَالَ: قَالَ أَبُو جَعْفَر لَا تُعَادُ الصَّلَاةُ إِلَّا مِنْ خَمْسَةٍ الطَّهُورِ وَ الْوَقْتِ وَ الْقِبْلَةِ وَ الرُّكُوعِ وَ السُّجُودِ.

📚 Al-Faqih, vol. 1, p. 279

Imam Baqir (peace be upon him) said: 'Prayer is not repeated except for five things: purity (Wudu or Ghusl or Tayammum), time, Qibla, bowing, and prostration.'

✅ The above narration generally mentions the reasons for repeating the prayer, one of which is the Qibla, and its details are mentioned in other narrations.

2 عَنْ مُصَدِّقٍ عَنْ عَمَّارٍ عَنْ أَبِي عَبْدِ اللَّه قَالَ: فِي رَجُلٍ صَلَّى عَلَى غَيْرِ الْقِبْلَةِ فَيَعْلَمُ وَ هُوَ فِي الصَّلَاةِ قَبْلَ أَنْ يَفْرُغَ مِنْ صَلَاتِهِ قَالَ إِنْ كَانَ مُتَوَجِّهاً فِيمَا بَيْنَ الْمَشْرِقِ وَ الْمَغْرِبِ فَلْيُحَوِّلْ وَجْهَهُ إِلَى الْقِبْلَةِ سَاعَةَ يَعْلَمُ وَ إِنْ كَانَ مُتَوَجِّهاً إِلَى دُبُرِ الْقِبْلَةِ فَلْيَقْطَعِ الصَّلَاةَ ثُمَّ يُحَوِّلُ وَجْهَهُ إِلَى الْقِبْلَةِ ثُمَّ يَفْتَتِحُ الصَّلَاةَ.

📚 Al-Kafi, vol. 3, p. 285

Imam Sadiq (peace be upon him) said about a person who prayed not facing the Qibla and realizes it during the prayer, before finishing it: 'If he was facing between the east and the west, he should turn his face towards the Qibla the moment he realizes it. And if his back was to the Qibla, he must stop his prayer and then turn his face towards the Qibla and start the prayer from the beginning.'

3 عَنِ الْحُسَيْنِ بْنِ عُلْوَانَ عَنْ جَعْفَرِ بْنِ مُحَمَّدٍ عَنْ أَبِيهِ عَنْ عَلِيٍّ أَنَّهُ كَانَ يَقُولُ مَنْ صَلَّى عَلَى غَيْرِ الْقِبْلَةِ وَ هُوَ يَرَى أَنَّهُ عَلَى الْقِبْلَةِ ثُمَّ عَرَفَ بَعْدَ ذَلِكَ فَلَا إِعَادَةَ عَلَيْهِ إِذَا كَانَ فِيمَا بَيْنَ الْمَشْرِقِ وَ الْمَغْرِبِ.

📚 Qurb al-Isnad, p. 54

Imam Sadiq (peace be upon him) narrated from his father that Ali (peace be upon him) would say: 'Whoever prays not facing the Qibla, while he thought he was facing the Qibla, and then realizes it afterwards, he is not obligated to repeat the prayer, provided he was facing between the east and the west.'

4 عَنْ سُلَيْمَانَ بْنِ خَالِدٍ قَالَ: قُلْتُ لِأَبِي عَبْدِ اللَّهِ الرَّجُلُ يَكُونُ فِي قَفْرٍ مِنَ الْأَرْضِ فِي يَوْمِ غَيْمٍ فَيُصَلِّي لِغَيْرِ الْقِبْلَةِ ثُمَّ تُصْحِي فَيَعْلَمُ أَنَّهُ صَلَّى لِغَيْرِ الْقِبْلَةِ كَيْفَ يَصْنَعُ قَالَ إِنْ كَانَ فِي وَقْتٍ فَلْيُعِدْ صَلَاتَهُ وَ إِنْ كَانَ مَضَى الْوَقْتُ فَحَسْبُهُ اجْتِهَادُهُ

📚 Al-Kafi, vol. 3, p. 285

Sulayman said: 'I said to Imam Sadiq (peace be upon him): 'A person is in a desert land on a cloudy day and he prays his prayer not facing the Qibla, and then the clouds clear and he realizes that he prayed not facing the Qibla. What should he do?' The Imam said: 'If the prayer time is still there, he must repeat his prayer, and if the time has passed, his ijtihad (his effort and investigation to find and guess the direction of the Qibla) is sufficient for him.'

5 مُحَمَّدُ بْنُ الْحَسَنِ فِي النِّهَايَةِ قَالَ: قَدْ رُوِيَتْ رِوَايَةٌ أَنَّهُ إِذَا كَانَ صَلَّى إِلَى اسْتِدْبَارِ الْقِبْلَةِ ثُمَّ عَلِمَ بَعْدَ خُرُوجِ الْوَقْتِ وَجَبَ عَلَيْهِ إِعَادَةُ الصَّلَاةِ

📚 Al-Nihayah, p. 64

Shaykh Tusi says in the book Al-Nihayah: 'It has been narrated in a tradition that whenever a person prays with his back to the Qibla and then realizes it after the time has passed, repeating the prayer is obligatory for him.'

✅ Points from the above narrations and others:

1 A person who thinks he is facing the Qibla and realizes during the prayer that he is not, if he is facing between the east and the west, he should immediately turn his face towards the Qibla while still in the prayer and continue. But if he was facing beyond the area between the east and the west, or his back was to the Qibla, he must stop his prayer and start over from the beginning.

2 A person who, due to not knowing the direction of the Qibla, made an effort, investigation, and search and concluded a certain direction and prayed towards it, and later realizes that he was not facing the Qibla, if the prayer time is still remaining, he should repeat the prayer. If the prayer time has passed, there is no need to repeat the prayer.

3 In the case of praying intentionally towards a direction other than the Qibla, the prayer is void and must be repeated, whether it is a deviation from the Qibla or turning one's back to it.

4 In the case of praying beyond the area between the east and the west and praying with one's back to the Qibla, in all certain cases and in the case of the time having passed with ijtihad and effort to find the Qibla, according to the narrations such as the fifth narration, as a precaution, the prayer should be repeated.