Some scholars said that distinguishing characteristics should take precedence over the established habit, even if she knows her habit. This is one of the two reports from Ahmad and the position of al-Shafi‘i, because it is not unlikely that, when irregular bleeding began, her habitual cycle changed. If the distinguishing characteristics coincide with her habit, the matter is clear. But if they conflict with her habit—for example, if her habit was at the beginning of the month, but she did not see the distinguishing signs until the middle of the month—then the two conflict. Should the distinguishing characteristics be given precedence, or should the habit be given precedence? There is a difference of opinion.

Some scholars maintain that the habit should take precedence. This is the well-known position in the school of Imam Ahmad, and it is the apparent meaning of the hadith: the Messenger ﷺ instructed Umm Habibah bint Jahsh, may Allah be pleased with her, to refrain from prayer for the length of time that her menstrual period had previously kept her from it (1). Moreover, this is more precise and less likely to cause confusion for the woman, since the distinguishing signs may appear at the beginning of one month, in the middle of the next, and at the end of the third; they may even change for her. But if we say, “Adhere to your established habit,” that is easier and more manageable for her. This preference is clear.

Yet the reasoning of those who hold that she should instead rely on the distinguishing signs is also strong. They say: As long as we have distinguishing signs—this blood being thick, black, and foul-smelling, and that blood being red, thin, and odorless—how can we say that this is irregular bleeding when the former is recognizable?!

Third: if she has neither an established habit nor distinguishing signs—that is, the bleeding began from the outset and continued with her at a uniform rate—then she has neither a habit nor