Wherefore, my beloved brethren, let every man be swift to hear, slow to speak, slow to wrath: For the wrath of man worketh not the righteousness of God.
"hear"-Greek-akouo = hear or understand
We should try to understand where someone is coming from at all times. We shouldn't just assume anything but seek understanding. In order to do that, we have to keep our mouths shut and listen--truly listen. When we spout off in anger, we often cause the other person to retaliate in anger. The end result is not anything that glorifies God.
To worketh the righteousness of God we must seek to understand and show mercy and grace just as Christ Jesus did for us.