Abdullah bin Umar divorced his wife while she was menstruating, during the lifetime of the Messenger of Allah ﷺ. So Umar bin Khattab asked the Messenger of Allah ﷺ about it, and the Messenger of Allah ﷺ said, "Tell him to take her back and keep her until she becomes pure, then menstruates again, then becomes pure again. After that, if he wishes he may keep her, and if he wishes he may divorce her before touching her. That is the waiting period during which Allah has commanded that women be divorced."
حدثني يحيى عن مالك
أن عبد الله بن عمر طلق امرأته وهي حائض على عهد رسول الله ﷺ فسأل عمر بن الخطاب رسول الله ﷺ عن ذلك فقال رسول الله ﷺ مره فليراجعها ثم يمسكها حتى تطهر ثم تحيض ثم تطهر ثم إن شاء أمسك بعد وإن شاء طلق قبل أن يمس فتلك العدة التي أمر الله أن يطلق لها النساء