"There will be rulers over you, who will leave the sunnah like this," and he pointed to the origin of his finger. "If you were to leave these rulers alone, they will bring great affliction and disaster. There has been no previous ummah except that the first thing they left from their religion was the sunnah, and the last to be left was the salat , and were not these rulers shy and afraid from people, they would not pray". 

 
Abdullah Bin Mas'ud radiyAllaahu 'anhu [Mustadrak al Hakim 8584, Ad Dhahabi said as per the conditions of Bukhari and Muslim.]