It is narrated from Sayyiduna Ma'qil bin Yasar (may Allah be pleased with him) that his sister was divorced by her husband, and then he wished to take her back, but Ma'qil (may Allah be pleased with him) prevented her. So Allah, the Mighty and Majestic, revealed this verse concerning that: "And when you divorce women and they complete their waiting period, do not prevent them from marrying their former husbands when they agree between themselves in a fair manner" [Al-Baqarah: 232].
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17609