I asked Ibn Umar about a man who divorced his wife while she was menstruating.He said, "Do you know Abdullah bin Umar? He divorced his wife while she was menstruating, so Umar went to the Prophet ﷺ, who ordered him to take her back."I asked, "Is that divorce counted?"He replied, "What do you think? If he becomes incapable and acts foolishly?"
حدثنا نصر بن علي الجهضمي حدثنا عبد الأعلى قال حدثنا هشام عن محمد
سألت ابن عمر عن رجل طلق امرأته وهي حائض فقال تعرف عبد الله بن عمر طلق امرأته وهي حائض فأتى عمر النبي ﷺ فأمره أن يراجعها قلت أيعتد بتلك قال أرأيت إن عجز واستحمق
Bukhari narrated it in the Book of Divorce, Chapter on Taking Back a Menstruating Wife, hadith no. 5333, and Muslim, in the Book of Divorce, Chapter on the Prohibition of Divorcing a Menstruating Wife Without Her Consent, and that if One Violates This the Divorce Still Takes Effect and He Is Ordered to Take Her Back, hadith no. 9/1471, from the hadith of Muhammad bin Sirin, through this same chain.