For menstruation revolves around it. Our evidence is what 'A'ishah reported, saying: Fatimah bint Abi Hubaysh came to the Messenger of Allah (peace and blessings of Allah be upon him) and said: O Messenger of Allah, I have irregular bleeding and do not become pure; shall I cease praying? The Prophet (peace and blessings of Allah be upon him) replied: "That is only a vein, and it is not menstruation. So when the menstruation begins, leave off prayer; and when it ends, wash the blood from yourself and pray." Agreed upon (9). In the versions of al-Nasa'i and Abu Dawud: "When it is menstrual blood, it is black blood that is known; so refrain from prayer. When it is the other, perform wudu', for it is only a vein" (11). Ibn 'Abbas said: As for when she sees the 'Bahrani' (distinctive/dark) blood, she shall leave off prayer. He also said: By Allah, she will never see the blood that is truly blood after her days of menstruation except like the washings of meat water. The hadith of Umm Salamah merely points to the consideration of habit, and there is no dispute regarding it. The hadith of Fatimah is one of the three upon which menstruation revolves.

Section: The apparent meaning of al-Khiraqi’s words is that the one with distinguishing characteristics (mumayyizah), when she recognizes the distinction, observes it without the need for repetition. This is also the apparent meaning of Ahmad’s words in what we have narrated from him. Ibn 'Aqil said the same; because the meaning of 'distinction' (tamyiz) is that one of the two types of blood is distinguished from the other by its quality, and this is found from the very first instance. Al-Shafi'i held this view as well. Al-Qadi and Abu al-Hasan al-Amidi said: The one with distinguishing characteristics only observes from the distinction what has been repeated twice or three times, based on the two narrations regarding how habit is established. Our evidence is the saying of the Prophet (peace and blessings of Allah be upon him): "When the menstruation begins, leave off prayer; and when it ends, wash the blood from yourself and pray." He commanded her to leave off prayer when the menstruation begins without the consideration of any other matter, then extended this until the time it ends. Furthermore, because the distinction is a sign by its very nature, it does not require adding anything else to it, just like the habit. According to al-Qadi, she only observes from the distinction what conforms to the habit, because he requires repetition, and whenever it is repeated, it becomes a habit.