Chapter on the Ages That Children Are Commanded to Pray
Tahdhīb al-Aḥkām|Volume 2|Book 1|Chapter 18
عَنْهُ عَنْ مُحَمَّدِ بْنِ اَلْحُسَيْنِ عَنْ صَفْوَانَ عَنِ اَلْعَلاَءِ عَنْ مُحَمَّدِ بْنِ مُسْلِمٍ عَنْ أَحَدِهِمَا عَلَيْهِمَا اَلسَّلاَمُ: فِي اَلصَّبِيِّ مَتَى يُصَلِّي فَقَالَ إِذَا عَقَلَ اَلصَّلاَةَ قُلْتُ مَتَى يَعْقِلُ اَلصَّلاَةَ وَ تَجِبُ عَلَيْهِ فَقَالَ لِسِتِّ سِنِينَ
From him, from Muhammad ibn Al-Husayn, from Safwan, from Al-‘Ala’, from Muhammad ibn Muslim, from one of the two (Imams عليه السلام), peace be upon them:
Imam عليه السلام (was asked) regarding when a child should begin to pray. Imam عليه السلام said: "When he understands the prayer." I asked: “When does he understand the prayer and it becomes obligatory upon him?” Imam عليه السلام said: "At six years old."
- Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 411
- Ṣaḥīḥ al-Tahdhīb, p. 251