Anas bin Sirin reported,

I said to Ibn Umar, "Tell me about your divorce of your wife."He said, "I divorced her while she was menstruating, so I mentioned that to Umar bin Khattab , who in turn mentioned it to the Prophet ﷺ. The Prophet ﷺ said, 'Order him to take her back, and when she becomes pure, let him divorce her during her state of purity.'"I asked him, "Did you count that divorce, the one you pronounced while she was menstruating?"He replied, "Why would I not count it? Even if I had been incapable or acted foolishly."

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عن أنس بن سيرين قال

قلت لابن عمر حدثني عن طلاقك امرأتك قال طلقتها وهي حائض قال فذكرت ذلك لعمر بن الخطاب رضي الله عنه فذكره للنبي ﷺ فقال النبي ﷺ مره فليراجعها فإذا طهرت فليطلقها في طهرها قال قلت له هل اعتددت بالتي طلقتها وهي حائض قال فما لي لا أعتد بها وإن كنت قد عجزت واستحمقت