He who is slow to wrath has great understanding, but he who is impulsive exalts folly.
It takes great understanding of human nature to seek to control our anger. We must understand ourselves and the things that trigger our anger. We must understand others and know when they are trying to “push our buttons” and when they are not. Either way, it takes understanding to choose to not be provoked and even to forgive. And it takes understanding of God to seek His power to help control our wrath.
Matthew Henry commented on the second part of the verse this way: “Unbridled passion is folly proclaimed: He that is hasty of spirit, whose heart is tinder to every spark of provocation … thinks to magnify himself, whereas really he exalts his own folly.”