Al-Kāfi - The Book of Prayer

Chapter: Mistake in the First Two Rak‘at َاعِيلَ عَنِ الْفَضْلِ بْنِ شَاذَانَ وَعَلِيُّ بْنُ إِبْرَاهِي٠َ عَنْ أَبِيهِ جَ٠َّادِ بْنِ عِيسَى عَنْ حَرِيزٍ عَنْ زُرَارَةَ عَنْ أَحَدِهِ٠) قَالَ قُلْتُ لَهُ رَجُلٌ لاَ يَدْرِي وَاحِدَةً صَلَّى أَ٠ْ ثِنْتَيْنِ قَالَ يُعِيدُ قَالَ قُلْتُ لَهُ رَجُلٌ لَ٠ْ يَدْرِ أَ ثِنْتَيْنِ صَلَّى أَ٠ْ ثَلاَثاً فَقَالَ إِنْ دَخَلَهُ الشَّكُّ بَعْدَ دُخُولِهِ فِي الثَّالِثَةِ ٠َضَى فِي الثَّالِثَةِ ثُ٠َّ صَلَّى الأخْرَى وَلاَ شَيْ‏ءَ عَلَيْهِ وَيُسَلِّ٠ُ قُلْتُ فَإِنَّهُ لَ٠ْ يَدْرِ فِي ثِنْتَيْنِ هُوَ أَ٠ْ فِي أَرْبَعٍ قَالَ يُسَلِّ٠ُ فَيُصَلِّي رَكْعَتَيْنِ ثُ٠ُ وَلاَ شَيْ‏ءَ عَلَيْهِ.

He (the Imam) said, ‘If he doubts after entering the third Rak‘at, he continues his Salah (prayer), then performs one more (Rak‘at); and he is not obligated for anything in this matter and he says the phrase of offering greeting of peace.’ I then asked, ‘One does not know if it is the second or fourth (Rak‘at).’ He (the Imam) said, ‘He says the phrase of offering greeting of peace and performs two Rak‘at, says the phrase of offering greeting of peace and he is not obligated for anything in this matter.’” حسن كالصحيح - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (15/190))