When you see what is going on inside them, your hatred will fall off. You will only have compassion. If you see somebody agitated, angry, have you ever felt compassion for them? Feeling that way is not pleasant for them. No one ever likes feeling agitated or angry. If we don’t feel compassion when we see others’ mistakes, we are bound to get angry ourselves. 
The cause of anger is the lack of total knowledge of what is happening inside that man or that woman. Showing anger itself is not wrong, but being unaware of your anger only hurts you. Sometimes you can show anger purposefully. There is a difference. You may get angry with your children. You can act tough or maybe shout at them if they put themselves in danger. 
There is a place for showing anger, but when you get angry yourself, what is happening to you? You are shaken completely. Are you ever happy with the decisions you have made or the words you have spoken when you are angry? No, because you lose your total awareness. If you are completely aware and you are acting angry, that is fine. The type of anger that turns into fear and hatred comes when we do not know the situation totally when we don’t put ourselves into the other person’s shoes.
I am not saying these emotions are good or bad, right or wrong. We are looking at what the consequences are. In fact, when anger comes, what can you do? You may think a hundred times, “Oh, I shouldn’t get angry,” but when the mood comes, it comes like a thunderstorm. You are unable to control it. All your presumptions, your notions, and your promises simply go in vain. They do not stand, they do not hold. You are swept by your emotions. Emotions are 20-30 times more powerful than the thoughts and promises you make. Understanding this mechanism opens your heart. 
In fact, anger is an instrument. Anger is essential when you are able to be in control of it, when you are able to know it, how to use it, where to use it, and how to apply it. That takes skill. The art of handling your own mind. Knowledge and anger are mutually dependent. Knowledge and love are mutually dependent. This knowledge gives a possibility for you to be flowering in life at any moment, anywhere, anytime. 
Maybe you are walking on the beach, suddenly you are in love with the whole entire universe, sun, moon, stars, the sunset, the waves on the beach, and the wind in the trees. Everything appears to be very lively to you. So alive that you become that moment, and it stirs something deep inside you.