Chapter on Following the Sunnah and Evidence of the Book

12. Ali ibn Ibrahim has narrated from his father from al-Nawfali from al-Sakuni from abu ‘Abdallah from his ancestors (the Imams عليه السلام who have said the following. “Imam Ali عليه السلام said, ‘There are two kinds of Sunnah, (traditions). There is a Sunnah in obligations and following such Sunnah is guidance and its disregard is misguidance. There is a Sunnah, (tradition), in none obligatory issue. The following of this kind of Sunnah is a virtuous deed and its disregard for other matters is a sin.’”