Musannaf Ibn Abi Shayba 27:436

Ghundar narrated to us, from Shu'bah, from al-Hakam, from Mus'ab bin Sa'd, from Sa'd bin Abi Waqqas, who said: The Messenger of Allah, may Allah bless him and grant him peace, left Ali bin Abi Talib behind in the expedition of Tabuk. So he said: "O Messenger of Allah, do you leave me behind with the women and the children?" He said: "Are you not pleased that you are to me in the position of Harun to Musa, except that there is no prophet after me?"