Section III: What is Haram to Fast
Firstly: Fasting the days of Eid
It is haram to fast on the two days of Eid: al-Fitr and al-Adha. Consensus has been quoted over this by: Abu Ja`far al-Tabari, Ibn al-Mundhir, al-Tahawi, Ibn Hazm, Ibn `Abd al-Barr, Ibn Rushd, Ibn Qudamah, and al-Nawawi.
Secondly: Days of celebration
1. Dates of the days of celebration:The days of celebration are the eleventh, twelfth, and thirteenth of the month of Dhu al-Hijjah.
2. Ruling of fasting the days of celebration:It is haram to fast the days of celebration.
This is by agreement of the four schools of jurisprudence, the position of the Zahiris, and the majority of scholars.
Thirdly: Fasting the day of doubt
1. Defining the day of doubt:The day of doubt is the thirtieth of Sha`ban if the moon was not legally sighted the night before.
2. Ruling of fasting the day of doubt:It is haram to fast the day of doubt with the intention that it is in case it's the first of Ramadan or to error on the side of caution. This is the position of the Malikis, Shafi`is,
a narration from Ahmad, and a group of the Salaf. It is also the choice of al-Jassas, Ibn Hazm, Ibn `Abd al-Barr, and Ibn `Uthaymin.
Fourthly: The woman fasting voluntarily without her husband's permission 1. Ruling of a woman fasting voluntarily without her husband's permission:It is haram for the woman to fast voluntarily without her husband's permission, and this is by agreement of the four schools of jurisprudence.
2. Ruling of a man breaking his wife's voluntary fast without her permission:If a woman fasts voluntarily without her husband's permission then he may break her fast if he has need of her. This is by agreement of the four schools of jurisprudence.