Al-Hasan (may Allah have mercy on him) says that Ma'qil bin Yasar (may Allah be pleased with him) married his sister to a man, who then divorced her, so she became separated from him. Then that man sent a proposal of marriage to Ma'qil's (may Allah be pleased with him) sister, but Ma'qil bin Yasar (may Allah be pleased with him) refused and said: I gave you my honoured one as your wife, then you divorced her, and now you have come again with a proposal of marriage. By Allah! Now I will not marry her to you. The woman too wished to return to him. So Allah revealed this verse: "And when you divorce women and they reach the end of their waiting period, do not prevent them from marrying their husbands" [Surah al-Baqarah: 232], to the end of the verse. Ma'qil (may Allah be pleased with him) said: Yes, I will marry her to you.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13750