Musannaf Ibn Abi Shaybah

It is narrated from Azhar bin Abdullah that Ubadah bin Samit came from Syria to perform Hajj, then arrived in Medina and went to Hazrat Uthman and said, "O Uthman! Shall I not inform you of something that I heard from the Holy Prophet (peace and blessings be upon him)?" Hazrat Uthman replied, "Why not?" Hazrat Ubadah bin Samit said, "I heard the Holy Prophet (peace and blessings be upon him) say: Soon there will come rulers over you who will command you to do things that you recognize, and they will appoint governors whom you do not know (i.e., whom you do not understand). Thus, obedience to such rulers is not obligatory upon you."