Al-Kāfi
Hadith 13743ـ عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ مُحَمَّدِ بْنِ عِيسَى عَنْ يُونُسَ عَنْ عَبْدِ الله بْنِ سِنَانٍ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ الْسَّلام) قَالَ إِذَا كُنْتَ لاَ تَدْرِي أَرْبَعاً صَلَّيْتَ أَوْ خَمْساً فَاسْجُدْ سَجْدَتَيِ السَّهْوِ بَعْدَ تَسْلِيمِكَ ثُمَّ سَلِّمْ بَعْدَهُمَا.
3. Ali ibn Ibrahim has narrated from Muhammad ibn ‘Isa from Yunus ibn ‘Abd al-Rahman from ‘Abd Allah ibn Sinan who has said the following: “Abu ‘Abd Allah (a.s.), has said, ‘If you do not know whether you have performed four or five; then perform two Sujud (prostrations) because of mistake after Salam (the phrase of offering greeting of peace) and after the two Sujud (prostrations), say Salam.’”