So, according to one (1) of the two legal opinions held by scholars who stipulate ritual purity for the person performing tawaf: if a menstruating woman, someone in a state of major ritual impurity, a person lacking minor ablution, or anyone carrying a visible impurity nevertheless circumambulates the Kaʿbah, the tawaf is still deemed valid, but an expiatory sacrifice becomes obligatory. He must offer blood: either a sheep, or—in the cases of menstruation and major ritual impurity—a camel (2), whereas only a sheep is required for minor impurity.
The ban on a menstruating woman performing tawaf (3) is sometimes justified on the grounds that tawaf resembles prayer (4); at other times it is explained by the fact that she is barred from entering the mosque (5), just as she is forbidden from it
… that she must offer a sacrificial animal (dam), whereas the sounder view is that no sacrifice is required).
He also says (26/241): “Whoever claims that ritual purity is obligatory for tawaf and a condition thereof should note that its status as a condition here is no greater than its status in the prayer. It is well known that the conditions of prayer are waived when one is unable to fulfil them; therefore, waiving the conditions of tawaf in case of incapacity is even more appropriate. This is the conclusion that has presented itself to me in this matter. There is no power nor might except with Allah, the Most High, the Magnificent. Were it not for people’s urgent need to know and practice this ruling, I would not have ventured to discuss it, since I have found no prior treatment of the issue. Ijtihad (independent reasoning) in situations of necessity is what Allah has commanded us to undertake. If what I have said is correct, it is the ruling of Allah and His Messenger—praise be to Allah. If what I have said is wrong, it is from me and from Satan; Allah and His Messenger are free of error, and the one who errs is pardoned.”
(1) In MSS A and B: “wa-fi”.
(2) In MS D: “aw”.
(3) In MS B: “wa-qad”.
(4) The word “salat” (prayer) is absent in MS B.
(5) The phrase “min al-masjid” (“from the mosque”) appears in MS A as “ma‘a al-hadath” and in MS B as “min al-hadith”.}