Halakhah zu Schemuel II 16:11

It is from the roots of the commandment that a person know and put into his heart that everything that happens to him - good and bad - the cause of it coming to him is from God, blessed be He. And from the hand of man - from the hand of a man to his brother - there would not be anything without the will of God, blessed be He. Hence, when a person caused him pain or hurt him, he should know for himself that his [own] sins caused [it], and that God, may He be blessed, ordained this for him. And he should not place his thoughts to taking vengeance from [the one who pained him], since he is not the cause of his evil, but rather the sin is the cause; like David, peace be upon him, stated (II Samuel 16:11), "leave him to curse, since the Lord told him [so]" - he made the matter depend upon his [own] sin, and not upon Shimei ben Gera. And there is also a great benefit found in this commandment, in quieting a dispute and removing enmity from the heart of people. And when there is peace among people, God, may He be blessed, will make peace for them.