For a Woman, One Day Is Twenty-Four Hours
Question
A certain woman has hayd sometimes for two days and sometimes for three days continuously, and then it stops completely. After a day or two it comes again: sometimes it happens two or three times, sometimes it stays for an hour or two and stops; then after a day or two it comes once or so and ceases. Altogether this came to seven days. It always happens like this: it lasts at least four days and at most seven days. What should be done in such a case; what is the ruling of Allah and the Messenger?
Answer
This woman will be considered in hayd for seven days; after that she will perform ghusl and pray. One day and night is 24 hours: from 12 o'clock until 12 o'clock of the following day the day and night will be called complete.
Source: Fatawa Mahmudiyya
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