When the Messenger of Allah ﷺ wanted to leave Ali behind, Ali said to him, "What will people say about me if you leave me behind?"He replied, "Are you not content to be to me as Harun was to Musa, except that there is no prophet after me," or, "there shall be no prophet after me?"
حدثنا شاذان أسود بن عامر حدثنا شريك عن عبد الله بن محمد بن عقيل
لما أراد رسول الله ﷺ أن يخلف عليا رضي الله عنه قال قال له علي ما يقول الناس في إذا خلفتني قال فقال ما ترضى أن تكون مني بمنزلة هارون من موسى إلا أنه ليس بعدي نبي أو لا يكون بعدي نبي
Its isnad is hasan because of Sharik and Abdullah bin Muhammad bin Aqeel, and the hadith is found in the Sihah, and it has already appeared at 1583. It is in Bukhari 7/71, no. 3706 (Fath), and Muslim 4/1870, no. 2404, both in the Book of the Virtues of the Companions, the merits of Ali.