made one month correspond to each menstrual cycle. Accordingly, in the normal pattern Allah has established for women, a woman menstruates once each month. The Sunnah has also clarified that the istibrāʾ of a menstruating slave woman is completed by one period, so the month stands in place of the period.

Second: All these precautions and safeguards exist to preserve lineage and strengthen family roots, lest the “waters” be mixed, lineage be lost, and ancestral ties disappear. The Prophet ﷺ cursed anyone who claims descent from other than his true father. Allah, Exalted is He, says: “Call them by their fathers’ names” (Qur’an 33:5), and He says: “Those who are bound by the womb are nearer to one another in the Book of Allah” (Qur’an 8:75).