Qays bin Abi Hazim (may Allah have mercy on him) said: In my presence a man asked al-Mughirah bin Shu'bah (may Allah be pleased with him) about a man who had divorced his wife one hundred times. He said: Three divorces make the wife unlawful, and the 97 are excess.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 14970