Hazrat Thanvi (may Allah Ta’ala bless him) said;

“It has been narrated in a Hadith that if you hear that a mountain has moved from its place then accept it, but if you hear about a person that his internal attributes have changed then do not accept it. This tells us that with Riyazat (sustained effort) a person’s internal attributes do not subside totally, they just become attenuated.” 

What it means is that in the Hadith it has been negated that if you hear that a person’s anger has subsided completely, do not accept it, because a person’s internal attributes do not change completely. However, through Riyazat (sustained effort) and Suhbat (companionship) this anger can be brought under control. Then a person doesn’t get angry all the time. He may get angry but only in situations where Shariah permits him to get angry, and even in that anger he does not cross limits set by Shariah.