Yunus bin Bukayr al-Shaybani يونس بن بكير بن واصل الشيباني · The Book of Divorce

I said to Ibn'Umar (Allah be pleased with them): A person divorcedhis wife while she was in the state of menses, whereupon he said: Do you know 'Abdullah b. Umar (Allah be pleased with them), for he divorced his wife in the state of menses. 'Umar (Allah be pleased with him) came to Allah's Apostle (ﷺ) and asked him, and he (the Holy Prophet) commanded him that he should take her back, and she started her 'Idda. I said to…