533 - Ishaq ibn Ibrahim narrated to us, he said: Isa ibn Yunus informed us, from al-Rabi' ibn Sabih, from Ata', who said: "Menstruation is fifteen [days]."

• And I asked Ahmad - again -, I said: A woman menstruates every month for sixteen days or seventeen days? He disapproved of that and said: "It cannot be," adhering to the fifteen-day limit.

• And I heard Ahmad - again - when he was asked: What is the minimum of menstruation? He said: "It is narrated from Ata' that he said: 'The shortest duration of menstruation is a day.' It was said: And its maximum? He said: 'They say: fifteen.'"

534 - And I heard Ishaq say: Sufyan ibn Abd al-Malik narrated to us, from Ibn al-Mubarak, who said: Al-Awza'i and Malik ibn Anas said: "There was a woman with us who would menstruate"; one of them said: "Fifteen days," and the other said: "She would menstruate for one day; a moderate menstruation."

535 - Ishaq narrated to us, he said: Hafs ibn Ghiyath informed us, from Ash'ath, from Ata', who said: "Menstruation is fifteen [days]."

536 - I also heard Ishaq say: Abd al-Rahman ibn Mahdi said: "The statement of Malik ibn Anas - where he says: 'Menstruation cannot be more than fifteen days' - that is only for a woman who does not know the time of her menstruation. Her ruling is what the Prophet (peace be upon him) commanded: that she should abandon prayer during the days of her usual periods, then perform ghusl and pray. This is because women's menstruation changes from time to time; perhaps her menstruation is five days, then it increases to more than ten, then it decreases, although it has not reached us that any woman menstruated more than fifteen days, except for one woman: seventeen days - according to what was described of her - and this is rare among women. Likewise [with] the two days; a woman called Umm al-'Ala' said: 'My menstruation has been two days since time immemorial,' and she remained that way until she reached menopause."