حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ الْحَنْظَلِيُّ، أَخْبَرَنَا عِيسَى، - وَهُوَ ابْنُ يُونُسَ - حَدَّثَنَا زَكَرِيَّاءُ، عَنْ أَبِي إِسْحَاقَ، عَنِ الْبَرَاءِ، أَنَّ آخِرَ، سُورَةٍ أُنْزِلَتْ تَامَّةً سُورَةُ التَّوْبَةِ وَأَنَّ آخِرَ آيَةٍ أُنْزِلَتْ آيَةُ الْكَلاَلَةِ ‏.‏

Abu Ishaq said that he heard al-Bara' b. 'Azib (Allah be pleased with him) say: The last complete sura revealed (in the Holy Qur'an) is Sura Tauba (i e. al-Bara'at, ix.), and the last verse revealed is that pertaining to Kalala. Translation Not Available

Book reference: Sahih Muslim Book 23 Hadith 3941
Web reference: Sahih Muslim Book 11 Hadith 1618 c