1ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنِ ابْنِ أَبِي عُمَيْرٍ عَنْ حَمَّادٍ عَنِ الْحَلَبِيِّ قَالَ سُئِلَ أَبُو عَبْدِ الله (عَلَيْهِ الْسَّلام) عَنْ رَجُلٍ سَهَا فَلَمْ يَدْرِ سَجْدَةً سَجَدَ أَمْ ثِنْتَيْنِ قَالَ يَسْجُدُ أُخْرَى وَلَيْسَ عَلَيْهِ بَعْدَ انْقِضَاءِ الصَّلاَةِ سَجْدَتَا السَّهْوِ.

1. Ali ibn Ibrahim has narrated from his father from ibn abu ‘Umayr from Hammad from al-Halabiy who has said the following: “Abu ’Abd Allah, ‘Alayhi al-Salam, was asked about a man who becomes confused and does not know if he has done one or two Sajdah (prostrations). He (the Imam) said, ’He performs another Sajdah (prostration) and after completion of Salah (prayer) two Sajdah (prostration) because of mistake is not necessary.’”

2ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنِ الْحُسَيْنِ بْنِ سَعِيدٍ عَنْ مُحَمَّدِ بْنِ سِنَانٍ عَنِ ابْنِ مُسْكَانَ عَنْ أَبِي بَصِيرٍ قَالَ سَأَلْتُ أَبَا عَبْدِ الله (عَلَيْهِ الْسَّلام) عَنْ رَجُلٍ شَكَّ فَلَمْ يَدْرِ سَجْدَةً سَجَدَ أَمْ سَجْدَتَيْنِ قَالَ يَسْجُدُ حَتَّى يَسْتَيْقِنَ أَنَّهُمَا سَجْدَتَانِ.

2. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from al-Husayn ibn Sa‘id from Muhammad ibn Sinan from ibn Muskan from abu Basir from who has said the following: “I once asked abu ’Abd Allah, ‘Alayhi al-Salam, about a man who doubts and does not know if he has performed one or two Sajdah (prostrations). He (the Imam) said, ‘He performs Sajdah (prostration) to ascertain that it is two Sajdah (prostrations).”’

3ـ عَنْهُ عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ أَبِي نَصْرٍ وَعَلِيِّ بْنِ مُحَمَّدٍ عَنْ سَهْلِ بْنِ زِيَادٍ عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ أَبِي نَصْرٍ عَنْ أَبِي الْحَسَنِ (عَلَيْهِ الْسَّلام) قَالَ سَأَلْتُهُ عَنْ رَجُلٍ صَلَّى رَكْعَةً ثُمَّ ذَكَرَ وَهُوَ فِي الثَّانِيَةِ وَهُوَ رَاكِعٌ أَنَّهُ تَرَكَ سَجْدَةً مِنَ الأولَى فَقَالَ كَانَ أَبُو الْحَسَنِ (صلّى اللهُ عَلَيْهِ وَآلِه) يَقُولُ إِذَا تَرَكْتَ السَّجْدَةَ فِي الرَّكْعَةِ الأولَى وَلَمْ تَدْرِ وَاحِدَةً أَمْ ثِنْتَيْنِ اسْتَقْبَلْتَ الصَّلاَةَ حَتَّى يَصِحَّ لَكَ أَنَّهُمَا اثْنَتَانِ.

3. It is a narration from him (narrator of previous Hadith) by Ahmad ibn Muhammad from Ahmad ibn Muhammad ibn abu Nasr and Ali ibn Muhammad from Sahl ibn Ziyad from Ahmad ibn Muhammad ibn abu Nasr who has said the following: “I once asked abu al-Hassan, ‘Alayhi al-Salam, about a man who performs one Rak’at of Salah (prayer), then he remembers in the second Rak’at in Ruku’ (bowing down on one’s knees) position that he has omitted one Sajdah (prostration) of the first Rak’at. He said, ‘Abu al-Hassan, ‘Alayhi al- Salam, would say that if you omit Sajdah (prostration) in the first Rak’at and do not know if it is one or two; perform Salah (prayer) again until it is correct to say that two Sajdah (prostrations) are performed.’”

4ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنْ عَمْرِو بْنِ عُثْمَانَ الْخَزَّازِ عَنِ الْمُفَضَّلِ بْنِ صَالِحٍ عَنْ زَيْدٍ الشَّحَّامِ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ الْسَّلام) فِي رَجُلٍ شُبِّهَ عَلَيْهِ وَلَمْ يَدْرِ وَاحِدَةً سَجَدَ أَمْ ثِنْتَيْنِ قَالَ فَلْيَسْجُدْ أُخْرَى.

4. Ali ibn Ibrahim has narrated from his father from ibn abu ‘Umayr from ‘Amr ibn ‘Uthman al-Khazzaz from al-Mufaddal ibn Salih from Zayd al-Shahham who has said the following: “About a man who doubts and does not know if he has performed one or two Sajdah (prostrations), abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘He performs one more Sajdah (prostration).”’