Yunus bin Jubair said “I asked ‘Abd Allah bin ‘Umar “A man divorced his wife while she was menstruating? He said do you know ‘Abd Allah bin ‘Umar? He said, yes. ‘Abd Allah bin ‘Umar divorced his wife while she was menstruating. So, ‘Umar came to the Prophet (ﷺ) and asked him (about this matter). He said Command him to take her back in marriage he may the divorce her in the beginning of the waiting period. I (Ibn Jubair) asked him “Will this divorce be counted? He said “Why not?” If he was helpless and showed his foolishness (that would have been counted)

English translation · Sunan Abu Dawud