Bismihi ta'ala
The mustahab days to fast are:
- The holy month of Rajab, if not the whole month, the first three days, mid three days (13, 14 & 15) and last three days.
- The holy month of Sha'baan [as above].
- Three days of any month, and the best way to do this is the first and last thursday of the lunhar month, and the mid Wednesday of the month (first wednesday from the second ten days of the month)
- Ayam al-Beidh of every month (13th, 14th and 15th).
- Monday and Thursday of every week.
- Ma'bath Day (27th Rajab)
- Birthday of the Prophet (s.a.w.) (17th Rabi' al-Awwal)
- Six days after Eid al-Fitr (2nd - 7th Shawwal)
- Dahu al-Ardh Day (25th Dhil-Qi'dah)
- Arafah Day (9th Dhul-Hijjah)
- Ghadir Day (18th Dhul-Hijjah)
- Mubahalah Day (24th Dhul-Hijjah)
- Nawruz Day.
And Allah knows best