Shaykhul islam ibn taymiyyah said:

 

“It was said to imam Ahmad bin Hanbal, a man fasts, prays and stays in seclusion at the masjid, is that more beloved to you or if he speaks against the people of bida’ (innovation)?”

 

He said: if he fasts, prays and stays in seclusion he benefits only himself, but if he speaks against the people of innovation, that benefits all the muslims so that is better.”

 

[Taken from majmu' al fatawa]