An envious man harms himself before he harms the person he envies, as was the case with Iblis: by his envy he brought the curse upon himself, whereas to Adam he brought about his election, guidance, elevation to the true contract, and his being chosen. Therefore be envied rather than envious, because the punishment of the envious is always worse than that of the envied; thus is provision apportioned.
So how does envying benefit the envious, and how does envy harm the envied? The root of envy lies in the blindness of the heart, and rejection of Allah's overflowing favour: they are two wings of disbelief. Through envy the son of Adam falls into endless grief and is utterly destroyed, and there is no way he can save himself. The envious does not really repent, for he continues to dwell upon and believe in his envy; indeed it is such an inherent part of his nature that it manifests itself unopposed and without apparent reason, causing him harm. A person's basic nature does not change, even with treatment.