It is narrated from Anas bin Sirin (may Allah have mercy on him) that he asked Sayyiduna Ibn Umar (may Allah be pleased with them both) about a man who divorced his wife while she was menstruating. He said: "Do you know Abdullah bin Umar? I divorced my wife while she was menstruating, so Sayyiduna Umar (may Allah be pleased with him) came to the Prophet (peace and blessings be upon him) and asked him about it, and he (peace and blessings be upon him) said: 'Tell him to take her back; then, when she becomes pure, let him divorce her, if he wishes, at the beginning of her waiting period ('iddah).'" Anas bin Sirin (may Allah have mercy on him) said: I asked: "Then is that divorce to be counted?" He said: "What else (that is, it certainly counts)?"
Imam al-Tabarani (may Allah have mercy on him) said: "No one narrated this hadith from al-Awwam bin Hamzah (may Allah have mercy on him) except Abu Bahr (may Allah have mercy on him)."