Al-Kāfi
Hadith 1835ـ عَنْهُ عَنْ أَبِيهِ عَنْ فَضَالَةَ بْنِ أَيُّوبَ عَنِ الْحَسَنِ بْنِ زِيَادٍ الصَّيْقَلِ عَنْ فُضَيْلِ بْنِ يَسَارٍ قَالَ قَالَ أَبُو جَعْفَرٍ (عَلَيهِ السَّلام) إِنَّ أَشَدَّ الْعِبَادَةِ الْوَرَعُ.
5. It is narrated from him (narrator of the Hadith above) from his father from Fadalah ibn Ayyub from al-Hassan ibn Ziyad al-Sayqal from Fudayl ibn Yasar from abu Ja’far who has said the following: “Abu Ja’far (a.s.) has said, ‘Restraining from worldly matters (sins) is the most intense form of worship.’”