Sahih Bukhari
Sahih Bukhari Volume 006, Book 060, Hadith Number 067.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 60. Prophetic Commentary on the Qur'an (Tafseer of The Prophet (PBUH))
Narrated By Ibn Abbas : The last Verse (in the Quran) revealed to the Prophet was the Verse dealing with usury (i.e. Riba).