It was reported that this Ayah was revealed about Ma`qil bin Yasar Al-Muzani and his sister. Al-Bukhari reported in his Sahih, when he mentioned the Tafsir of this Ayah (2:232), that the husband of the sister of Ma`qil bin Yasar divorced her. He waited until her `Iddah finished and then asked to remarry her, but Ma`qil refused. Then, this Ayah was sent down:

(...do not prevent them from marrying their (former) husbands.)

Abu Dawud, At-Tirmidhi, Ibn Abu Hatim, Ibn Jarir and Ibn Marduwyah and Al-Bayhaqi reported this Hadith from Al-Hasan from Ma`qil bin Yasar. At-Tirmidhi rendered this Hadith authentic and in his narration, Ma`qil bin Yasar gave his sister in marriage for a Muslim man during the time of Allah's Messenger . She remained with him for a while and he divorced her once and did not take her back until her `Iddah finished. They then wanted to get back with each other and he came to ask her for marriage. Ma`qil said to him, "O ungrateful one! I honored you and married her to you but you divorced her. By Allah! She will never be returned to you.'' But Allah knew his need for his wife and her need for her husband and He revealed:

(And when you have divorced women and they have fulfilled the term of their prescribed period, ) until He said:

(...and you know not.)

When Ma`qil heard the Ayah, he said, "I hear and obey my Lord.'' He then summoned the man and said, "I will honor you and let you remarry (my sister).'' Ibn Marduwyah added (that Ma`qil said), "And will pay (the expiation) for breaking my vow.''

Allah said:

(This (instruction) is an admonition for him among you who believes in Allah and the Last Day.) meaning, prohibiting you from preventing the women from marrying their ex-husbands, if they both agree to it,

(among you) O people,

(who believes in Allah and the Last Day.) meaning, believes in Allah's commandments and fears His warnings and the torment in the Hereafter. Allah said:

(That is more virtuous and purer for you.) meaning, obeying Allah's Law by returning the women to their ex-husbands, and abandoning your displeasure, is purer and cleaner for your hearts,

(Allah knows) the benefits you gain from what He commands and what He forbids.

(and you know not) the benefits in what you do or what you refrain from doing.

(233. The mothers should suckle their children for two whole years, (that is) for those (parents) who desire to complete the term of suckling, but the father of the child shall bear the cost of the mother's food and clothing on a reasonable basis. No person shall have a burden laid on him greater than he can bear. No mother shall be treated unfairly on account of her child, nor father on account of his child. And on the (father's) heir is incumbent the like of that (which was incumbent on the father). If they both decide on weaning, by mutual consent, and after due consultation, there is no sin on them. And if you decide on a foster suckling-mother for your children, there is no sin on you, provided you pay (the mother) what you agreed (to give her) on a reasonable basis. And fear Allah and know that Allah is All-Seer of what you do.)