This Ayah contains a command from Allah to the wives whose husbands die, that they should observe a period of `Iddah of four months and ten nights, including the cases where the marriage was consummated or otherwise, according to the consensus (of the scholars).
The proof that this ruling includes the case where the marriage was not consummated is included in the general meaning of the Ayah. In a narration recorded by Imam Ahmad and the compilers of the Sunan, which At-Tirmidhi graded Sahih, Ibn Mas`ud was asked about a man who married a woman, but he died before consummating the marriage. He also did not appoint a Mahr (dowry) for her. They kept asking Ibn Mas`ud about this subject until he said, "I shall give you my own opinion, and if it is correct then it is from Allah, while if it is wrong it is because of my error and because of (the evil efforts of) Satan. In this case, Allah and His Messenger are innocent of my opinion. She has her full Mahr.'' In another narration, Ibn Mas`ud said, "She has a similar Mahr to that of the women of her status, without stinginess or extravagance.'' He then continued, "She has to spend the `Iddah and has a right to the inheritance.'' Ma`qil bin Yasar Ashja`i then stood up and said, "I heard Allah's Messenger issue a similar judgment for the benefit of Barwa` bint Washiq.'' `Abdullah bin Mas`ud became very delighted upon hearing this statement. In another narration, several men from Ashja` (tribe) stood up and said, "We testify that Allah's Messenger issued a similar ruling for the benefit of Barwa` bint Washiq.''
As for the case of the widow whose husband dies while she is pregnant, her term of `Iddah ends when she gives birth, even if it occurs an instant (after her husband dies). This ruling is taken from Allah's statement:
﴿وَأُوْلَـتُ الاٌّحْمَالِ أَجَلُهُنَّ أَن يَضَعْنَ حَمْلَهُنَّ﴾
(And for those who are pregnant, their `Iddah is until they lay down their burden.) (65:4)
There is also a Hadith from Subay`ah Al-Aslamiyah in the Two Sahihs, through various chains of narration. Her husband, Sa`d bin Khawlah, died while she was pregnant and she gave birth only a few nights after his death. When she finished her Nifas (postnatal period), she beautified herself for those who might seek to engage her (for marriage). Then, Abu Sanabil bin Ba`kak came to her and said, "Why do I see you beautified yourself, do you wish to marry By Allah! You will not marry until the four months and ten nights have passed.'' Subay`ah said, "When he said that to me, I collected my garments when night fell and went to Allah's Messenger and asked him about this matter. He said that my `Iddah had finished when I gave birth and allowed me to get married if I wished.''