Al-Kāfi
Hadith 13893ـ حَمَّادٌ عَنِ ابْنِ أَبِي يَعْفُورٍ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ الْسَّلام) قَالَ قَالَ إِذَا شَكَكْتَ فَلَمْ تَدْرِ أَ فِي ثَلاَثٍ أَنْتَ أَمْ فِي اثْنَتَيْنِ أَمْ فِي وَاحِدَةٍ أَمْ فِي أَرْبَعٍ فَأَعِدْ وَلاَ تَمْضِ عَلَى الشَّكِّ.
3. Hammad has narrated from ibn abu Ya‘fur who has said the following: “Abu ‘Abd Allah (a.s.), has said, ‘If you doubt and do not know if you have performed three or two or one or four, perform Salah (prayer) again and do not continue with doubt.’”