Muhammad's wives
Muhammad was monogamous for 25 years. After his first wife Khadija bint Khuwaylid died, he proceeded to marry the wives listed below, and most of them were widows. Muhammad's life is traditionally delineated as two epochs: pre-hijra (emigration) in Mecca, a city in western Arabia, from the year 570 to 622, and post-hijra in Medina, from 622 until his death in 632. All but two of his marriages were contracted after the Hijra (migration to Medina). Of Muhammad's thirteen wives, at least two, Rayhana bint Zayd and Maria al-Qibtiyya, were referred to simply as concubines; however, there is debate among Muslims as to whether these two officially became his wives. Of his thirteen wives, only two bore him children, a fact which has been described as "curious" by Cornell University Professor of Near Eastern Studies David S. Powers.
Ahl al-Kisa
Some Sunni scholars remark that the "purification verse" was revealed concerning five people: Muhammad, Ali, Fatimah, Hassan and Husayn. Others maintain that the "purification verse" cannot refer to the inerrancy of the Imams because the context in which it occurs relates to the wives of Muhammad and necessitates that it, too, should refer to them, or that at the very least they cannot be excluded from the category it addresses. If it were to imply inerrancy, then the wives of Muhammad would also have to be inerrant, a belief that Sunni scholars do not hold. Shia scholars, however, do believe in the infallibility of Muhammad. Ibn Kathir in his tafsir of the relevant verse says "the [Sunni] scholars are unanimously agreed that [Muhammad's wives] were the reason for revelation in this case...but others may be included by way of generalization."