It is narrated on the authority of Tariq bin Shihab: It was Marwan who initiated (the practice) of delivering khutba (public address) before prayer on the Eid Day. A man stood up and said: Prayer should precede khutba. He (Marwan) remarked: This (practice) has been done away with. Upon this Abu Sa’id remarked: This man has performed (his duty) laid on him. I heard the Messenger of Allah (peace and blessings of Allah be to him) as saying: He who among you sees something abominable should modify it with the help of his hand; and if he has not strength enough to do it, he should do it with the tongue; and if he has not strength to do it, (even then) he should abhor it from the heart, and that is the last faith.
(Sahih Muslim)
This hadith throws a good deal of light on how the society is to be kept safe and secure from evil and corruption. It has been made obligatory for every Muslim to see to it that the moral health of the community does not deteriorate, and whenever there is any sign of decadence in any quarter it should be checked with determination.
Islam does not allow its followers to lead the life of a silent spectator in the world; it has made them duty-bound to eradicate evil, since once it is allowed to creep into the society, it corrodes it and the whole social structure crumbles down. It has, therefore, been enjoined upon the believers to take effective measures to fight against it.