If a menstruating woman becomes pure before night, should she abstain from all that breaks fast?
Should a woman observe fast and abstain from all that breaks it in Ramadan, if her menstruation ends and she becomes Tahir (ritually pure) after Fajr (Dawn) Prayer or after Zhuhr (Noon) Prayer? Or must she not observe the fast in this circumstance,
because the duration of fast is from the break of the dawn until sunset?
If menstruation ends and a woman becomes Tahir after the time when abstention from all that breaks Sawm enters, whether this occurs at the beginning of the day, in the middle of it, or at its end, then she has to abstain from all that breaks fast the rest of the day. This is according to the Saying of Allah (Exalted be He):
So whoever of you sights (the crescent on the first night of) the month (of Ramadan i.e. is present at his home), he must observe Saum (fasts) that month
This is also because of the sanctity of fast time for whoever is obliged to observe fast in this case. By the cession of the impediment (menstruation ends), the woman in the question has become obliged to observe fast. However, she has to make up for that day, because she did not observe fast all of the day; and observing fast in part of the day does not replace the fast of the whole day. Allah (Glorified and Exalted be He) says:
...and eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night), then complete your Saum (fast) till the nightfall.
Besides, she has to perform after-menstruation Ghusl (full ritual bath) so that she can offer the Obligatory Prayers. (Part No. 9; Page No. 60) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.