There are different reports about the last chapter and the last verse sent down upon the Prophet (pbuh). According to some reports, the last chapter which was revealed to the Prophet (pubh) was Chapter al-Nasr whereas some other reports consider Chapter al-Bara'ah (al-Tawbah) to be the last chapter. There are some narrations according to which verse 281 of Chapter al-Baqarah is the last verse whereas according to some other narrations the verse of 'Perfection' of Religion[i] was the last of the revealed verses. The correct view in this regard is to say that the last complete chapter which was sent down upon the Prophet, peace be upon him and his progeny, was Chapter al-Nasr which was revealed in the year of the conquest of Mecca; but the last verse which was sent down and which informs the Prophet (pbuh) of the completion of his mission was the verse of 'Perfection' of Religion. It is also likely that the last verse in terms of Ayatul Ahkaam (verses relating to the practical rules) might be the verse "And guard yourselves against a day in which you shall be returned to Allah "[ii] which has been recorded in Chapter al-Baqarah.
In order to reply to the above question, it is necessary to initially clarify as to which verse or Sura had been the last verse or Sura with which the gradual revelation of the Quran to the Prophet (pbuh) had been completed. There are different reports which introduce different verses as the last revealed Sura of the Quran. Below we shall provide a few examples:
1. The Ahlul-Bayt (a.s.) have been narrated as having said that the last Sura which was sent down upon the Prophet (pbuh) is Chapter al-Nasr. In this verse, there is the good news regarding the absolute victory of Shari'ah whose pillars had been strengthened and which people were accepting and embracing in groups. The Holy Prophet's companions became happy at the revelation of this verse because it gave the happy news of absolute victory of Muslims over the infidels and also the good news of the fortification of the pillars of the religion. However, Abbas, the Prophet's uncle became sad when this chapter was revealed. It is said that he even wept upon the revelation of the chapter. The Prophet (pbuh) enquired him as to why he was weeping?
He answered, "I assume the verse indicates that it is the end of your mission."
"Yes, it is as you have assumed," said the Prophet (pbuh). The Prophet passed away two years after the revelation of the said chapter.
Imam Sadiq (a.s.) said: "The last of all chapters is Chapter al-Nasr" [When cometh the help of God and victory…]. It has also been narrated from Ibn-e Abbas that he said that the last chapter which was revealed to the Prophet was Chapter al-Nasr.
2. It has been stated in another tradition that the last chapter was Chapter al-Bara'ah (al-Tawbah) whose initial verses were revealed in the ninth Hegira year and which the Holy Prophet (pbuh) ordered Imam Ali (a.s) to read out to a group of pagans.
3. It has been reported in different textual sources that the last verse which was revealed to the Prophet (pbuh) was verse the following: "And guard yourselves against a day in which you shall be returned to Allah; then every soul shall be paid back in full what it has earned, and they shall not be dealt with unjustly." When this verse was brought down by Gabriel, he ordered the Prophet to put the verse in between the verse of 'usury' and the verse of 'debt' (i.e. between verses 280 and 282) of al-Baqarah. It is said that the Prophet (pbuh) did not live more than 21 or according to another report 7 days after the revelation of this verse.
4. Ahmad bin Abi Ya'qub, better known as Ibn Wazih al-Ya'qubi (292 A.H.) writes in his Tarikh al-Ya'qubi as such: "It has been said that the last verse sent down upon the Prophet (pbuh) was this verse "This day have I perfected your religion for you, completed My favour upon you, and have chosen for you Islam as your religion". Then he says: "According to me, it is correct and acceptable, and this verse was revealed on the day when Ali bin Abi Talib (a.s.) was appointed as the successor of the Holy Prophet (pbuh) at Ghadir Khum."
There is no doubt that Chapter Al-Nasr has been revealed before Chapter al-Bara'ah because Chapter al-Nasr was revealed in the year of the conquest of Mecca which was the eighth Hegira year whereas Chapter al-Bara'ah was revealed after the conquest of Mecca. In order to reconcile between these two sets of narrations, it can be said that the last complete chapter which was revealed to the Prophet (pbuh) was Chapter al-Nasr and the last chapter considering its initial verses was Sura al-Bara'at. As for verse 281 of al-Baqara [i.e. and guard yourselves against a day in which you shall be returned to Allah], according to Mavardi's report, it was revealed at Mina during the Farewell Pilgrimage of the Prophet (pbuh). Therefore, it cannot be the last verse because the verse of 'Perfection' of Religion was revealed at Ghadir Khum after the Prophet's return from the farewell pilgrimage.
It can be said as a conclusion that Ibn Wazih al-Ya'qubi's view is more correct because Chapter al-Bara'ah was revealed in the ninth Hegira year after the conquest of Mecca and Chapter al-Maedah was revealed in the tenth Hegira year during which the Prophet performed the Farewell Pilgrimage. In addition, Chapter al-Maeda consists of a number of rules and injunctions concerning the end of the wars and consolidation of Islam and its perfection as indicated in verse 3 of the same chapter and which is also coherent with the last verse.
The correct view is to say that the last complete chapter which was sent down upon the Prophet, peace be upon him and his progeny, was Chapter al-Nasr which was revealed in the year of the conquest of Mecca but the last revealed verse which informs the Prophet (pbuh) of the completion of his mission was the verse of 'Perfection' of Religion i.e. verse 3 of chapter al-Maedah. It is also likely though that the last verse in terms of Ayatul Ahkaam (verse regarding the practical rules) might be the verse "And guard yourselves against a day in which you shall be returned to Allah" which has been recorded in Chapter al-Baqarah.
In view of the above, the gradual descent (revelation) of the Holy Quran was completed in the tenth Hegira year (the year of Farewell Hajj of the Prophet (pbuh)).
 - Muhammad bin Hasan, Hurr Ameli, Wasail al-Shi'ah, vol.7, pg.371.
 - Tabarsi, Fadhl bin al-Hassan, Majma'ul Bayan, vol.10, pg.884, Nasir Khosro Publications, Tehran, 1372.
 - Huwaizi, Eid Ali, vol.5, pg.690, Ismailiyan Publications, 1415 A.H.
 - Shubbar, Sayyid Abdullah, Tafsir Shubbar, pg.199, Nashr Darul Balaghah, Beirut, 1412.
 - al-Baqara: 281
 - Majma'ul Bayan, vol.3, pg.196.
 - al-Maedah: 3 "الْیَوْمَ أَکْمَلْتُ لَکُمْ دینَکُمْ وَ أَتْمَمْتُ عَلَیْکُمْ نِعْمَتی وَ رَضیتُ لَکُمُ الْإِسْلامَ دینا"
 - Ya'qubi, Ibn Wazih, Tarikh al-Ya'qubi, vol.2, pg.35.
 - al-Baqarah: 281
 - Tafsir al-Mavardi (al-Nokat al-'Uyoon), vol.1, pg.63; Zarkashi, Al-Burhan, vol.1, pg.186.
 - Ma'refat, Muhammad Hadi, Uloom Qurani, pg.76.