Abdullah bin Umar (may Allah be pleased with them both) narrates that he divorced his wife during her menstruation in the time of the Messenger of Allah (peace and blessings be upon him). Umar (may Allah be pleased with him) mentioned this (to the Messenger of Allah, peace and blessings be upon him), so the Messenger of Allah (peace and blessings be upon him) said: Command him to take her back until she becomes pure. Anas bin Sirin (may Allah have mercy on him) says: I asked Ibn Umar (may Allah be pleased with them both): Did you count that divorce (or not)? He replied: Why not.