The Chapter on Obligatory Prayers
Man Lā Yaḥḍuruh al-Faqīh|Volume 1|Book 1|Chapter 30
وَ رُوِيَ عَنْ مَعْمَرِ بْنِ يَحْيَى قَالَ سَمِعْتُ أَبَا عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ يَقُولُ: «إِذَا جِئْتَ بِالْخَمْسِ اَلصَّلَوَاتِ لَمْ تُسْأَلْ عَنْ صَلاَةٍ وَ إِذَا جِئْتَ بِصَوْمِ شَهْرِ رَمَضَانَ لَمْ تُسْأَلْ عَنْ صَوْمٍ.
It is narrated from Ma'mar ibn Yahya, who said: I heard Imam Jafar ibn Muhammad Al-Sadiq عليه السلام say: "If you perform the five daily prayers, you will not be questioned about any other prayer, and if you observe the fast of the month of Ramadan, you will not be questioned about any other fasting."
- Ṣaḥīḥ al-Faqīh, p. 33