Sahih al-Bukhari 4654
Narrated Al-Bara:
The last Verse that was revealed was: 
'They ask you for a legal verdict: Say: Allah directs (thus) about Al-Kalalah (those who leave no 
descendants or ascendants as heirs).' And the last Sura which was revealed was Baraatun (9) .
حَدَّثَنَا أَبُو الْوَلِيدِ، حَدَّثَنَا شُعْبَةُ، عَنْ أَبِي إِسْحَاقَ، قَالَ سَمِعْتُ الْبَرَاءَ ـ رضى الله عنه ـ يَقُولُ آخِرُ آيَةٍ نَزَلَتْ ‏{‏يَسْتَفْتُونَكَ قُلِ اللَّهُ يُفْتِيكُمْ فِي الْكَلاَلَةِ‏}‏ وَآخِرُ سُورَةٍ نَزَلَتْ بَرَاءَةٌ‏.‏