Yunus bin Jubayr said: I asked Ibn Umar (may Allah be pleased with him): "May a man divorce his wife while she is menstruating?" He said: "Do you know Ibn Umar? He divorced his wife while she was menstruating, so Sayyiduna Umar (may Allah be pleased with him) asked the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) commanded him to take her back." I said: "Will that be counted as one divorce?" He said: "(What) if he was helpless or acted foolishly?"
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 14919