Sahih Muslim
The Book on Government (Kitab Al-Imara)
Book Number: 020 / Hadith Number: 4533
It has been narrated on the authority of Ibn 'Umar that the Holy Prophet (may peace be upon him) said: It is obligatory upon a Muslim that he should listen (to the ruler appointed over him) and obey him whether he likes it or not, except that he is ordered to do a sinful thing. If he is ordered to do a sinful act, a Muslim should neither. listen to him nor should he obey his orders.