Ibn 'Umar (RA) reported that he divorced his wife while she was in the state of menses. 'Umar (RA) made mention of it to Allah's Apostle (ﷺ) and he said: Command him to take her back, then divorce her when she is pure or she is pregnant.
Hadith ReferenceSahih Muslim / The Book of Divorce / Hadith: 1471