What is the ruling of bleeding again before 15 days of purity elapse?

Ibn Māzah al-Bukhārī (d.616 AH) states that the Aṣl (principle), according to Imām Abū Yūsuf (d.182 AH), and the concluding view of Imām Abū Ḥanīfah (d.150 AH), is that if the days of purity are less than fifteen days, the bleeding is regarded as continuous. In such instances, identifying the hayḍ days involves examining historical menstrual cycles and patterns of purification. However, if both sets of bleeding were divided by fifteen days or more, the cycles would be considered independent, and independently Ḥayḍ.

The aṣl al-binā’ (underpinning principle) of this ruling, extrapolated from the Tātārkhāniyyah, is based on the idea that a purity cycle (ṭuhr) must see its full course. A purity cycle lasting less than fifteen days (ṭuhr nāqiṣ) is not considered a valid cycle of purity, and does not legally separate between two sets of bleeding to establish a change in rulings. For a menstrual cycle to be established, a complete ṭuhr(purity) period must elapse.

Both menstruation and travel directly influence acts of worship, notably fasting and prayer. Imam al-Sarakhsī (d.483 AH) highlights this analogy, suggesting that the fifteen-day period borrows its principle from the travel duration, which necessitates complete prayer. The minimum menstruation duration is equated to three days, akin to the shortest permissible travel length, contemporarily interpreted into miles. This parallel is drawn because both conditions — menstruation and travel — distinctly affect one’s capacity to engage in prayer and fasting.

A second attempt at rationalising the ruling is found in the books of Fiqh; Allah Most High has established the cycle for those who don’t have regular menstruation, like prepubescent girls or elder women, aligning it with the typical patterns of menstruation and purity: Fifteen days for each. This means that when a cycle is divided, it splits evenly, with half the month, or fifteen days, attributed to menstruation and the other half to purity.

However, adjustments to this division — be it less than fifteen days for purity or more than three days for menstruation — are only established based on the actual presence and manifestation of menstrual blood during that period. This perspective and understanding is attributed to Imām Abū Manṣur al-Māturīdī (d.333 AH).

In the Muhīṭ, Ibn Māzah al-Bukhārī (d.616 AH) presents a clear and concise representation of the discussion stating it is deemed suitable for half of the month to be designated as the menstrual period (hayḍ), while the remaining half is considered a state of purity (ṭuhr). However, an important exception arises when the actual physical occurrence of hayḍdemonstrates a reduction in its duration to less than half of the month. Regardless of the specific circumstances, it is crucial to note that the purity period is always constricted to a minimum of fifteen days to establish a second cycle of menstruation. If this is not the case, the two phases of bleeding shall be merged and understood to be singular, and the days of haydshall be determined through historic cycles as mentioned above.

‘Allāmah Bābirtī (d.786 AH), echoing the prevailing view of the Fuqahā’, refutes the two aforementioned rationales. He asserts that details regarding durations, lengths, and numbers aren’t subjects for rational deduction. Instead, these rulings are firmly rooted in explicit scriptural texts, emphasising that they are derived and established solely from divine revelation rather than human reasoning.