Is one period of purity or part of a menstrual cycle sufficient for Istibra' (proving non-pregnancy)?
General Chapter
Al-Mughni
Book of Waiting Periods ('Iddah)
Primary text
The definitive ruling requires more than a single period of purity or only a portion of a menstrual flow to establish Istibra'. This position is held by the majority of scholars. The evidence against relying on only one period is the Prophetic saying: "A pregnant woman shall not have intercourse with her until she delivers, and a non-pregnant woman shall not have intercourse with her until she completes Istibra' with one menstrual cycle (hayda)." Furthermore, the evidence confirming freedom from pregnancy is the menstrual flow itself, as a pregnant woman does not menstruate. Purity does not provide such clear indication of non-pregnancy.
Supporting text
Some companions of Malik maintain that once a woman enters the flow of her menses, her Istibra' is complete, claiming this as the Madhhab of Malik. Al-Shafi'i, in one opinion, states that one complete period of purity suffices if she passes away during her menses; if she sees blood for the second menses, her waiting period is concluded. These views are often based on the premise that the pure intervals (Aṭhār) count as the obligatory cycles (Quru').