What is the minimum duration of menstruation?
Chapter on Menstruation
Al-Mughni
Book of Purification
Primary text
The minimum duration of menstruation is one day according to the sound position in the Madhhab of Abu Abdullah (Ahmad). This position holds that since menstruation is mentioned absolutely in the Law without a specified limit, and has no linguistic or legal definition, reference must be made to custom and habit. Evidence for this limited view includes reports of women who customarily menstruate for one day, and reports from Atiqah and Ahmad regarding women whose cycles were consistently fifteen days or one day, respectively. The Hadith used by those suggesting a minimum of three days (Hadith of Wathilah) is weak due to narrators being weak or unknown, and the Hadith of Anas stating a range up to ten days is deemed baseless by Ibn Uyaynah and weak by Ahmad.
Supporting text
It is held by Al-Thawri, Abu Hanifa, and his companions that the minimum is three days and the maximum is ten days, citing the Hadith of Wathilah ibn al-Asqa'. A view from Malik is that there is no minimum limit, allowing it to be only an hour, arguing that setting a minimum would require a woman to abstain from prayer until that minimum period passes, which is not legislated.