The reason the jurists parted company is that two distinct ḥadīths bear on the question.

The first is the report transmitted by ʿĀʾishah from Fāṭimah bint Abī Ḥubaysh: “The Prophet—peace and blessings be upon him—ordered her, while she was suffering chronic bleeding, to leave off the prayer for the same number of days during which she had previously menstruated, then to bathe and perform her prayers.” A report of Umm Salamah with the same purport, already cited, was likewise recorded by Mālik.

The second ḥadīth is the narration preserved by Abū Dāwūd from Fāṭimah bint Abī Ḥubaysh. When she experienced istiḥāḍah, the Messenger of Allah—peace and blessings be upon him—said to her: “Menstrual blood is dark and recognizable; when you see that, refrain from prayer, but when the blood is of the other kind, perform ablution and pray, for it is only a vein.” Abū Muḥammad Ibn Ḥazm judged this report sound.

On the strength of these two texts, some scholars opted to prefer one over the other (tarjīḥ), while others sought to harmonize them (jamʿ).

Those who favored the ḥadīth of Umm Salamah and similar reports made the decisive factor the number of days. Mālik—may Allah be pleased with him—counted the days only in the case of a menstruant who fears that her flow has become istiḥāḍah; he did not apply that criterion to a mustaḥāḍah who suspects that her bleeding is actually ḥayḍ—meaning he ignored both the number of days and their place in the month even when she knew them. Yet the textual evidence in fact concerns the mustaḥāḍah who doubts menstruation; thus he applied the ruling in the secondary case and not in the primary, which is indeed curious—ponder it well.

Those who preferred the ḥadīth of Fāṭimah bint Abī Ḥubaysh took the color of the blood as the touchstone. Among them were some who, in addition to color, considered how many of the days of istiḥāḍah could validly count as a period of purity; this, according to ʿAbd al-Wahhāb, is one narration from Mālik. Others ignored that additional factor.

Scholars who reconciled the two reports said: the first ḥadīth applies to a woman who knows both the number of her days in the month and their timing, whereas the second concerns one who knows neither the number nor the timing but can distinguish the blood’s color. Still others held that if she cannot distinguish the blood, does not know when her days fall in the month, and whether or not she knows their number, she should proceed in accordance with the ḥadīth of Ḥamnah bint Jaḥsh, which al-Tirmidhī declared sound. In that report the Messenger of Allah—peace and blessings be upon him—said to her: “It is only a kick from Satan; therefore regard yourself as menstruating for six or seven days—Allah knows best—then bathe.” The full version of this ḥadīth will be cited later under the rulings of the mustaḥāḍah concerning purity.

These, then, are the well-known issues in this chapter, and they fall, broadly speaking, into four areas:

1. discerning the transition from purity to menstruation;
2. discerning the transition from menstruation to purity;
3. discerning the transition from menstruation to istiḥāḍah; and
4. discerning the transition from istiḥāḍah back to menstruation, which is