The prophet said: “The first to enter through this door is the Imam of the pious, the chief of Muslims, the head of the religion, the seal of the wasis, and the leader of those whose foreheads radiate with the mark of faith,” whereupon `Ali entered and he, peace be upon him and his progeny, stood up happily excited, hugged him and wiped his sweat saying: “You shall fulfill my covenant, convey my message, and after me clarify whatever seems to be ambiguous.”
Reference: ● Abu Na’im in his Hilyat al-Awliya’ from Anas ● Ibn Abul Hadid on page 450, Vol. 2, of his Sharh Nahjul Balaghah
Aal-e-Qutub Aal-e-Syed Abdullah Shah Ghazi 