Why was the abrogating verse (And those of you who die and leave wives behind, they shall wait on their own for four months and ten days) placed before the abrogated verse (And those of you who die and leave wives behind, a will for their wives, provision for a year without expulsion) in the order of the Mus'haf, even though the abrogated verse was revealed before the abrogating one? And does this order affect the understanding of the Qur’an?

The arrangement of the verses of the Holy Quran and the composition of its surahs were determined by the Prophet, peace be upon him, and not by the ijtihad (independent reasoning) of the Companions. Gabriel, peace be upon him, used to come to the Prophet, peace be upon him, and convey to him Allah's command to place a certain verse in a certain place within the surah. Some might believe that a verse whose ruling has been abrogated should not be written in the Mushaf, but its continued inscription therein has many benefits, such as the reward for recitation and compliance with the command, and it is a divine injunction that cannot be altered. Two verses in the Quran precede others in the Mushaf but abrogate what follows them in arrangement: the verse concerning the woman whose husband has died, which abrogated the verse of the will for a year, and the verse "O Prophet, We have made lawful for you your wives," which abrogated "It is not lawful for you [to marry other] women after." Scholars have differed regarding the verse "And [make] a will for their wives of maintenance for a year." Most of them are of the view that it is abrogated by the verse "four months and ten [days]," which precedes it in the Mushaf but was revealed later. Others are of the view that it is not abrogated and that the verse of the year was a recommended will, not an obligatory one.