Narrated Al-Hasan:The sister of Ma'qil bin Yasar was divorced by her husband who left her till she had fulfilled her term of 'Iddat (i.e. the period which should elapse before she can Remarry) and then he wanted to remarry her but Ma'qil refused, so this Verse was revealed:-- "Do not prevent them from marrying their (former) husbands

English translation · Sahih al-Bukhari