Al-Kāfi - Volume 2 > Disbelief
Hadith #1

1ـ عِدَّةٌ مِنْ أَصْحَابِنَا عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنِ الْحَسَنِ بْنِ مَحْبُوبٍ عَنْ دَاوُدَ بْنِ كَثِيرٍ الرَّقِّيِّ قَالَ قُلْتُ لأبِي عَبْدِ الله (عَلَيهِ السَّلام) سُنَنُ رَسُولِ الله (صَلَّى اللهُ عَلَيْهِ وآلِه) كَفَرَائِضِ الله عَزَّ وَجَلَّ فَقَالَ إِنَّ الله عَزَّ وَجَلَّ فَرَضَ فَرَائِضَ مُوجَبَاتٍ عَلَى الْعِبَادِ فَمَنْ تَرَكَ فَرِيضَةً مِنَ الْمُوجَبَاتِ فَلَمْ يَعْمَلْ بِهَا وَجَحَدَهَا كَانَ كَافِراً وَأَمَرَ رَسُولُ الله بِأُمُورٍ كُلُّهَا حَسَنَةٌ فَلَيْسَ مَنْ تَرَكَ بَعْضَ مَا أَمَرَ الله عَزَّ وَجَلَّ بِهِ عِبَادَهُ مِنَ الطَّاعَةِ بِكَافِرٍ وَلَكِنَّهُ تَارِكٌ لِلْفَضْلِ مَنْقُوصٌ مِنَ الْخَيْرِ.

1. A number of our people have narrated from Ahmad ibn Muhammad from al- Hassan ibn Mahbub from Dawud ibn Kathir al-Raqqi who has said the following: “Once I asked abu ‘Abd Allah (a.s.) ‘Are the traditions, Sunan of the Messenger of Allah like the obligations Allah, the Most Majestic, the Most Holy, has sanctioned?’ The Imam said, ‘Allah, the Most Majestic, the Most Holy, has sanctioned obligations that are compulsory for the servants (of Allah). Whoever ignores an obligation of the compulsory ones; does not perform it and rejects it, he becomes an unbeliever. The Messenger of Allah has commanded certain matters to be performed and they all are good deeds. One does not become an unbeliever for ignoring a few of the obligations that Allah, the Most Majestic, the Most Holy, has commanded His servant to perform, however, he has ignored a virtue and has cut down goodness.’”