Sayyiduna Abu Umamah al-Bahili (may Allah be pleased with him) says: I heard the Prophet (peace and blessings be upon him) say in the sermon of the Farewell Pilgrimage: "O people, there will be no prophet after me, and there will be no Ummah after you." After that the narrator mentioned the full hadith.
Al-Tabarani recorded it; the narrators of one of its two routes are thiqat (trustworthy), and there is weakness in some of its narrators.