He that is slow to anger is better than the mighty; Proverbs 16:32
Being slow to anger is easier said than done, and note we are not told never to be angry, only slow to anger. There are some injustices that deserve our anger, God’s as well, but our anger is only productive if comes from a holy calm of the soul. To be moved by passion and reaction is not a show of strength. When our actions originate from a calm soul, heart, and mind we are closer to the perfect freedom.
Know that it is not difficult to live among others who are also calm and gentle, where everyone enjoys peace, and all agree with us. However it is a true test of grace to walk and talk in peace when we are surrounded by hard and perverse persons, who are disorderly and go contrary to us. It is during this ordeal we need to ask God to send his holy calm and let it settle in our soul.