Ordering Good and Forbidding Evil

From Aboo Sa'eed al-Khudree (radiyallaahu 'anhu) who said: Allaah's Messenger (salallaahu 'alaihi wa'sallam) stood amongst us to deliver an address, and from his address was that he said: Indeed it is about to occur that I will be called and will respond. Then after me will follow rulers over you who say what they have knowledge of, and act upon what they know. Obedience to them is obedience to me, and you remain like that for a time. Then there will follow rulers over you after them who say what they do not have knowledge of and act according to what they do not have knowledge of. So whoever is sincere to them and assists them, or strengthens them then they are destroyed and have caused destruction. Accompany them with your bodies and differ with them by your actions, and bear witness for the doer of good from them that he is a doer of good, and for the doer of evil that he is a doer of evil