Hisham bin Urwah (may Allah have mercy on him) narrates from his father (may Allah have mercy on him) that a man would divorce his wife and then take her back, and there was no limit at which this matter would come to an end. A man from the Ansar (may Allah be pleased with him) said to his wife: By Allah, I will never give you a place with me, nor will I let you become lawful for anyone else. The woman (may Allah be pleased with her) said: How is that? He said: I will divorce you, and when your 'iddah is about to be completed, I will take you back. Hisham bin Urwah (may Allah have mercy on him) said: She mentioned this matter to the Messenger of Allah (peace and blessings be upon him), complaining, so Allah Almighty revealed this verse: "Revocable divorce is twice; then either retain her in a fair manner or release her with kindness" [Surah al-Baqarah: 229]. So the people turned to it afresh, both those who had divorced and those who had not.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب العدد / 15560