LEV998 Great reward awaits the man who guards himself against envy and desire. For with most of the transgressions a man stands to suffer shame if he transgresses, and he restrains himself because of this. For example, he restrains himself from robbery and theft out of fear that he will be revealed, exposed, and publicized, and that he will be put to shame and suffer a great loss. But envy and desire are in the heart and not subject to public scrutiny, but only to one's conscience. About such matters it is written [this verse]: "And you should fear your God." Even though envy is an extremely evil trait, there is an area in which it is extremely good and noble--the area of fear of Hashem, as it is written (Mishlei 23:17): "Let your heart not envy sinners, but be in the fear of Hashem all the day." It is in this regard that our Rabbis of blessed memory said (Bava Bathra 21a): "The envy of the scribes increases wisdom." If one sees another learning, he should generate envy in his heart and say: "He learns a whole day; I will do likewise." The same applies to all mitzvos and good traits--everyone should envy his neighbor and seize upon his good traits. If one sees an evildoer with a single good trait, let him envy him for the trait and emulate it.