Muhammad bin Sirin (may Allah have mercy on him) said: Al-Hakam al-Ghifari was appointed governor over Khurasan. This reached Sayyiduna Imran bin Husayn (may Allah be pleased with him), so he searched for al-Hakam until he met him in al-Rahbah (an open square), and said: I have been searching for you since today; you have been sent to a great task. Do you remember the day when the Messenger of Allah (peace and blessings be upon him) said: "There is no obedience in disobedience to Allah"? He said: Yes. Imran (may Allah be pleased with him) said: Allahu akbar! I thought you had forgotten.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15525