The Book of the Rules of Inheritance
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، وَابْنُ، بَشَّارٍ قَالاَ حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، عَنْ أَبِي إِسْحَاقَ، قَالَ سَمِعْتُ الْبَرَاءَ بْنَ عَازِبٍ، يَقُولُ آخِرُ آيَةٍ أُنْزِلَتْ آيَةُ الْكَلاَلَةِ وَآخِرُ سُورَةٍ أُنْزِلَتْ بَرَاءَةُ .Abu Ishaq said that he heard al-Bara' b. 'Azib (Allah be pleased with him say:The last verse revealed (in the Holy Quran) is that pertaining to Kalala, and the last sura revealed is Sura al-Bara'at
From Sahih Muslim, whose reports the scholars accept as authentic.