Mishkat al-Masabih #3145

'Abdallah b. ‘Umar said he divorced a wife of his while she was menstruating and that when ‘Umar mentioned the matter to God’s Messenger he became angry and said, “He must take her back and keep her till she is purified, then has another period and is purified. If it then seems good to him to divorce her he may do so when she is pure from the menstrual discharge before having intercourse with her, for that is the period of waiting which God has commanded for the divorce of women.” A version has, “Command him to take her back, then divorce her when she is pure from the menstrual discharge, or pregnant.” (Bukhari and Muslim.)