The Messenger of Allah ﷺ said to Ali, "You are to me as Harun was to Musa, except that there is no prophet after me."
حدثنا وكيع حدثنا فضيل بن مرزوق عن عطية العوفي
قال رسول الله ﷺ لعلي أنت مني بمنزلة هارون من موسى إلا أنه لا نبي بعدي
Its chain of transmission is hasan, on account of Awfi and also on account of Fudayl bin Marzuk. In truth, the hadith of Fudayl deserved to be graded daif, since he was truthful but prone to error and inclined toward Shia views, and this hadith concerns the virtues of Ali, which the Shia cling to. However, the hadith itself is sahih, as it was narrated by Muslim (4/1870, no. 3404) in the virtues of Ali, by Tirmidhi (5/640, no. 4730) in the chapter on merits, where he said it is hasan gharib, and by Ibn Majah (1/45, no. 121) in the introduction.