What is required when a person vows to fast a month?
General Chapter
Al-Mughni
Book of Vows
Primary text
If a person vows to fast a month (*shahr*), they have the choice to either fast according to the lunar cycle, beginning from the first day of the new moon, or to fast thirty days by count. The requirement for consecutive fasting (*tatabu'*) in the vow of a month is subject to differing opinions.
Supporting text
One view mandates consecutive fasting, as stated by Abu Thawr, because the unqualified term 'month' implies continuity. The opposing view, held by Al-Shafi'i and Muhammad bin Al-Hasan, is that consecutive fasting is not required because 'month' refers to the period between two new moons or thirty days, and since fasting thirty days fulfills the vow, continuity is not mandatory, similar to a vow of thirty days.