Chapter on the Rulings on Forgetfulness (Ahkam al-Sahw)
Tahdhīb al-Aḥkām|Volume 2|Book 1|Chapter 16
اَلْحُسَيْنُ بْنُ سَعِيدٍ عَنْ فَضَالَةَ وَ صَفْوَانَ عَنِ اَلْعَلاَءِ عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ عَنْ أَحَدِهِمَا عَلَيْهِمَا اَلسَّلاَمُ قَالَ: سَأَلْتُهُ عَنِ اَلسَّهْوِ فِي اَلنَّافِلَةِ فَقَالَ« لَيْسَ عَلَيْكَ شَيْءٌ»
Al-Husayn ibn Sa‘id from Faddalah and Safwan from al-‘Ala’ from Muhammad ibn Muslim from one of the two (Imams عليه السلام), peace be upon them, who said:
I asked Imam عليه السلام about forgetfulness in the supererogatory prayer. Imam عليه السلام said: "There is nothing upon you."
- Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 369
- Ṣaḥīḥ al-Tahdhīb, p. 231