Musar su Salmi 91:10

While they were still walking they saw a snake dancing before them. Rabbi Shimon said, “This snake is surely going to perform some miracle. The snake ran on ahead and entangled itself with a certain viper. The nature of the viper is such that if it gazes at a human being or a human being gazes at it, the person immediately dies from the poison of its gaze, Heaven spare us. After the snake entangled itself with the viper they began striking each another until they both died. When they arrive at that spot and saw the two of them lying dead upon the road Rabbi Shimon recited the verse, “No evil shall befall you, and no plague shall come near your tent” (Tehillim 91:10). He continued, “The Holy One Blessed is He has created every creature to perform an errand. Thus we must not disparage anything that He has made, for it was created for the sake of its mission. Concerning this was it written, ‘Hashem is good to all and His mercies are upon all His works’ (Tehillim 145:9).”

The category of destructive agents mentioned above are called “Evil.” Concerning them it states, “No Evil shall befall you” (Tehillim 91:10). Their victim resembles a sick person who has before him every delicacy in the world, yet he is unable to enjoy any of it because of his sickness. Thus the miser derives no benefit from his deeds in this world or the next, other than the shrouds in which he is buried. This is the meaning of the verse in Koheles (6:2), “As for the man upon whom God bestows wealth, property and honor, but God does not give him dominion over it, this too is a sickly evil.” Therefore let a man be sure to do what is upright in the eyes of God and men. For, “a good name is better than fine oil” (Koheles 7:1). Then all will be well with him while he is here, he will pass from the world with a good name and he will also enjoy good fortune in the World to Come.