Assalaamu alaykum wa rahmatullaahi wa barakaatuhu Shaykh. This Ramadhan, I checked on the 14th day of my menses, a few mins before Fajr, and I strongly felt that was pure and decided to fast. Then, after the Fajr, I decided to make sure by rechecking the purity and found impurity so I broke my intention. Did I do wrong? I had to take a decision and felt that if I was correct I would miss a fast and if I turned out to be impure I would break my intention. What is the best action in such a situation; to intend and later break the intention or not to intend when having strong suspicions of being pure? I later checked and was still impure but I did become pure later that same day around 'Asr, praise be to Allaah. Is there a sin on me? Do I have to do anything, like pay an expiation? May Allaah reward you.
All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
There is no sin on you regarding what you did and there is no expiation on you. A woman is permitted to make the intention of fasting conditioned on being pure from menstruation if she has menses that end around that time, and then if she realizes that she became pure before the Fajr, she completes her fast, and she is not obliged to do anything, and her fast is valid.
Shaykh Ibn Taymiyyah held that her fast is valid in any case if she realizes that she became pure before the Fajr because she did what she was able to do.
In any case, you have to make up the fast of that day as long as you did not become pure before the Fajr. You are not required to do anything except for making up the fast of that day.
Allah knows best.
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