From Sahih Muslim (Hadith 6218):
Sa'd b. Abi Waqqas reported that Allah's Messenger (ﷺ) left 'Ali b. Abi Talib behind him (as he proceeded) to the expedition of Tabuk, whereupon he ('Ali) said:Allah's Messenger, are you leaving me behind amongst women and children? Thereupon he (the Holy Prophet) said: Aren't you satisfied with being unto me what Aaron was unto Moses but with this exception that there would be no prophet after me?
Reference: Muslim 6218