喜怒不當，是謂不明；暴虐不得，反受其賊。
To indulge in joy and anger at inappropriate times is known as lack of wisdom.
怨生不報，禍生於福。
One who tries, but fails, to hurt and mistreat others will himself be subject to attack.
Resentment arises from failure to repay favors; disasters arise from blessings.