Ibn Tawus narrates from his father that he heard Sayyiduna Ibn Umar (may Allah be pleased with them both) concerning a man who had divorced his wife while she was menstruating. He said: Do you know Abdullah bin Umar (may Allah be pleased with them both)? He said: Yes. He said: He divorced his wife while she was menstruating, so Sayyiduna Umar (may Allah be pleased with him) went to the Prophet (peace and blessings be upon him) and informed him, and he (peace and blessings be upon him) said: "Let him take her back."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 14924