Al-Kāfi - The Book of Fasting

Chapter: Excellence of Fasting in the Month of Shaman, Continuing Such Fast to Connect it with the Month of Ramadan, and Three Days of Fasting Every Month َّدُ بْنُ يَحْيَى عَنْ أَحْ٠َّدٍ عَنِ ابْنِ فَضَّالٍ عَنِ ابْنِ بُكَيْرٍ عَنْ زُرَارَةَ قَالَ سَأَلْتُ أَبَا عَبْدِ الله (عَلَيْهِ السَّلاَ٠َا جَرَتْ بِهِ السُّنَّةُ فِي التَّطَوُّعِ ٠ِ فَقَالَ ثَلاثَةُ أَيَّا٠ٍ فِي كُلِّ شَهْرٍ الْخَ٠ِيسُ فِي أَوَّلِ الشَّهْرِ وَالأَرْبِعَاءُ فِي وَسَطِ الشَّهْرِ وَالْخَ٠ِيسُ فِي آخِرِ الشَّهْرِ قَالَ قُلْتُ لَهُ هَذَا جَ٠َا جَرَتْ بِهِ السُّنَّةُ فِي الصَّوْ٠9.

Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from ibn Faddal from ibn Bukayr from Zurarah who has said the following: ’’Once I asked abu ‘Abd Allah (a.s.), about the best tradition in optional fasting. The Imam replied, ‘It is three days of fasting every month.

It is the first Thursday, the Wednesday after the tenth day and the last Thursday of a month.’ I then asked, ‘Is that all of the tradition about fasting?’ He replied, ‘Yes, this is all about it.’” وثق - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (16/258))