Believers, like anyone else, may naturally feel anger at certain events. However one of the most important indications of their virtuous character is their ability to control their anger. They know that no good will come of an uncontrolled, intense fury, and that they will just lose their ability to act reasonably or to be just. They avoid making wrong decisions that may harm both themselves and those around them. They abstain from it most importantly because they know that Allah will not approve of such a reaction and form of behaviour. For that reason believers exhibit steadfastness and forgiveness. Allah praises this feature of believers in the Qur'an in these words:
Those who give in times of both ease and hardship, those who control their rage and pardon other people—Allah loves the good-doers. (Surah Al 'Imran: 134)
Yet, "controlling rage" should not be misunderstood: it does not mean to accept everything as it is or being passive. Believers certainly take the necessary precautions, and try to prevent any wrongdoing or situations that may cause harm to other believers. However, they do not react emotionally; instead they try to find sensible ways to influence people's behaviour, or otherwise limit whatever damage is being caused.
Our Prophet (may Allah bless him and grant him peace) has this to say on controlling anger: