I asked Ibn Umar about a man who divorced his wife while she was menstruating.He replied, "Do you know Abdullah bin Umar? He divorced his wife while she was menstruating, so Umar went to the Prophet ﷺ to ask about it, and he ordered him to take her back and then wait until her next menstrual cycle to begin counting her waiting period."I then asked him, "When a man divorces his wife while she is menstruating, is that pronouncement of divorce counted?"He answered, "Of course. What if he proves incapable and acts foolishly?"
أخبرنا يعقوب بن إبراهيم قال حدثنا ابن علية عن يونس عن محمد بن سيرين
قلت لابن عمر رجل طلق امرأته وهي حائض فقال أتعرف عبد الله بن عمر فإنه طلق امرأته وهي حائض فأتى عمر النبي ﷺ يسأله فأمره أن يراجعها ثم يستقبل عدتها قلت له إذا طلق الرجل امرأته وهي حائض أيعتد بتلك التطليقة فقال مه وإن عجز واستحمق