And regarding their statement: "It is possible that the blood is irregular bleeding (fasad)." We respond: A ruling has already been established that it is menstruation regarding the cessation of prayer, its prohibition to the husband, and all other rulings of menstruation; thus, the same applies to the expiration of the 'idda. Furthermore, if the withholding of the ruling on the expiration of the 'idda is due to uncertainty, then once it is clarified that it is menstruation, we know that the 'idda had expired when she saw the blood, just as if he had said to her: "If you menstruate, you are divorced." Those who hold this view differ; some say the day and night are part of the 'idda, because it is blood by which the 'idda is completed, so it is part of it, like that which occurs during periods of purity. Others say it is not part of it; rather, its expiration is clarified by it. And because if we were to make it part of it, we would be necessitating an increase beyond three quru', but we prevent her from marriage until a day and a night have passed, and if her husband takes her back during that time, the return (raj'ah) would not be valid. This is the more correct of the two views.

1341 - Issue; he said: (And if she is a slave woman, then when she performs ghusl from the second menstruation...)

Most scholars of knowledge say: The 'idda of a slave woman by quru' is two quru'. Among them are 'Umar, 'Ali, Ibn 'Umar, Sa'id ibn al-Musayyab, 'Ata', 'Abd Allah ibn 'Utbah, al-Qasim, Salim, Zayd ibn Aslam, al-Zuhri, Qatadah, Malik, al-Thawri, al-Shafi'i, Ishaq, Abu Thawr, and the People of Opinion (ashab al-ra'y). According to Ibn Sirin, her 'idda is the same as that of a free woman, unless a tradition (sunnah) has passed to the contrary. This is also the view of Dawud, based on the saying of Allah the Almighty: {And divorced women shall wait for themselves three periods (quru')} (1). Our evidence is the saying of the Prophet (peace and blessings of Allah be upon him): "The quru' of a slave woman is two menstruations" (2). We have mentioned it, as well as the statements of 'Umar, 'Ali, and Ibn 'Umar, and we do not know of any opponent to them among the Companions, so it constitutes a consensus (ijma'). This specializes the generality of the verse. And because it is a numerical matter based on differentiation, the slave woman does not equal the free woman in it, just like the legal punishment (hadd).