1018. hadíth
وَ سَأَلَ اَلْفُضَيْلُ بْنُ يَسَارٍ أَبَا عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ: عَنِ اَلسَّهْوِ فَقَالَ «مَنْ يَحْفَظْ سَهْوَهُ فَأَتَمَّهُ فَلَيْسَ عَلَيْهِ سَجْدَتَا اَلسَّهْوِ وَ إِنَّمَا اَلسَّهْوُ عَلَى مَنْ لَمْ يَدْرِ أَ زَادَ فِي صَلاَتِهِ أَمْ نَقَصَ مِنْهَا.
Al-Fudail ibn Yasar asked Imam Jafar ibn Muhammad Al-Sadiq (a.s) about forgetfulness in prayer. Imam said: "Whoever remembers his forgetfulness and corrects it, there is no need for him to perform the two prostrations of forgetfulness (Sajdatay al-Sahw). However, forgetfulness applies to the one who does not know whether he has added to or missed part of his prayer."