Sahih Muslim , Book 11, Hadith 3942 (USC-MSA) ⓘ
Aba Ishaq reported this hadith on the authority of al-Bara' (Allah be pleased with him) with a slight variation of words, viz. the last sura that was revealed complete.
حَدَّثَنَا أَبُو كُرَيْبٍ، حَدَّثَنَا يَحْيَى، - يَعْنِي ابْنَ آدَمَ - حَدَّثَنَا عَمَّارٌ، - وَهُوَ ابْنُ رُزَيْقٍ - عَنْ أَبِي إِسْحَاقَ، عَنِ الْبَرَاءِ، بِمِثْلِهِ غَيْرَ أَنَّهُ قَالَ آخِرُ سُورَةٍ أُنْزِلَتْ كَامِلَةً .
also referenced under: Book 23, Hadith 16 (In-Book) & Hadith 1618 (Reference)