Hadith 4263
Nafi' reports: Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) informed him that he had divorced his wife once during her menstruation. Sayyiduna Umar (may Allah be pleased with him) asked the Prophet (peace and blessings be upon him) about this issue: He said, "Abdullah has divorced his wife during her menstruation." The Prophet (peace and blessings be upon him) said: "Tell Abdullah to take her back, then keep her with him until she becomes pure from this menstruation. Then, when she experiences menstruation a second time and becomes pure again, then if he wishes, he may divorce her before having intercourse with her, and if he wishes, he may keep her with him."