Ibn Umar divorced his wife while she was menstruating, so Umar asked the Prophet ﷺ about it. He instructed him to take her back, then leave her until she had another menstrual period, then leave her until she became pure, and then divorce her before touching her. That is the waiting period Allah commanded for divorcing women.Whenever Ibn Umar was asked about a man who divorced his wife while she was menstruating, he would say, "If you divorced her once or twice, the Messenger of Allah ﷺ commanded him to take her back, then leave her until she had another menstrual period, then leave her until she became pure, and then divorce her before touching her. But if you divorced her three times, you have disobeyed your Lord in what He commanded you concerning the divorce of your wife, and she is irrevocably separated from you."
و حدثني زهير بن حرب حدثنا إسمعيل عن أيوب
أن ابن عمر طلق امرأته وهي حائض فسأل عمر النبي ﷺ فأمره أن يرجعها ثم يمهلها حتى تحيض حيضة أخرى ثم يمهلها حتى تطهر ثم يطلقها قبل أن يمسها فتلك العدة التي أمر الله أن يطلق لها النساء قال فكان ابن عمر إذا سئل عن الرجل يطلق امرأته وهي حائض يقول أما أنت طلقتها واحدة أو اثنتين إن رسول الله ﷺ أمره أن يرجعها ثم يمهلها حتى تحيض حيضة أخرى ثم يمهلها حتى تطهر ثم يطلقها قبل أن يمسها وأما أنت طلقتها ثلاثا فقد عصيت ربك فيما أمرك به من طلاق امرأتك وبانت منك