It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that he divorced his wife while she was in her menstrual period. Sayyiduna Umar (may Allah be pleased with him) mentioned this to the Prophet (peace and blessings be upon him), so he said: Tell him to take his wife back, and when she becomes pure, then in those days of purity he may divorce her.