Imam Ali b. Moosa al-Reza (a.s.) while describing the status of Imamate said – Divine leadership is the rank of the Prophets, and the inheritance of the trustees. Divine leadership is the position of Vicegerency of the Honorable, the Exalted God and vicegerency of the Prophet. It is the position of Ameerul Momineen (a.s.). It is the Inheritance of Hasan (a.s.) and Husain (a.s.).
Oyoon Akhbaar al-Reza (a.s.) chap 20 trad 1