1) Fard Muayyan (command with stipulation of time)
2) Fad Ghair Muayyan (command without stipulation of time)
3) Wajib Muayyan (or dained with stipulation of time)
4) Wajid Ghair Muayyan (ordained without stipulation of time)
5) Masnun (the Prophet PBUH Percept)
6) Nafil (supererogatory)
7) Makruh (undesirable)
8) Haram (Forbidden)
One month’s fasting in a year during Ramadan is a command with stipulation of time.
If a person has missed fasts in Ramadan for some valid excuse or otherwise keeping these fasts at some later date is a command without stipulation of time.
Taking a vow to fast on some appointed day or date makes fasting on the particular day or date ordained with the stipulation of time. One such case could be of a person who has taken a vow to fast to please Allah say on the first of Rajab should he get through the examination for which he is to appear
Fasts for expiation and those to keep a vow without the stipulation of any day or date are fasts without the stipulation of time. An example of it could be of a person who has taken a vow to be on fast for three days should be stand first in the examination
There are no emphasized Precepts of the Prophet for fasts. But the fasts that have been exhorted to by him to keep them are known as Masnun fasts. These are i) fasts on the 9th and 10 [two days] of Muharram ii) a fast on Arfah (the 9th of Zul Hijjah) iii) fasts on Ayvam ul Abyad (brighter days ) 13,14,15 of every month from the lunar Hijrah calendar.
All fasts other than those falling under the category of commanded or ordained and the fasts that are the Prophet Percepts are classed as supererogatory. Some of these hold the promise of bountiful reward.l They are
i) Fasts on six days of Shawwal
ii) Fast on 15th of Shaban
iii) Fasts on Friday
iv) Fasts on Monday
v) Fasts on Thursday
The following fasts are undesirable
i) Fasts on Saturday only
ii) Fasts on Ashurrahs (10 muharram only)
iii) Fasts on Nauroze (a festival of Persians)
iv) Nafli fasts by a housewife without permission of her husband.
Fasting is forbidden on the following
i) the two days namely Eid-Fittar, Eid Ul Azha
ii) the three days of Tashriq 11,12,13 Zul hijjah