From Sahih Muslim (Hadith 4154):
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
Reference: Muslim 4154