It is narrated from Sayyiduna Abu Ayyub al-Ansari (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said to Sayyiduna Ali (may Allah be pleased with him): "Your position in relation to me is that of Harun (peace be upon him) in relation to Musa (peace be upon him), except that there is no prophet after me."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 4072