Envy devours good deeds just as a fire devours fuel
Hasad is of varying degrees:
1 – When a person wants the blessing to be taken away from his Muslim brother, even if it does not come to him; rather he does not like Allaah to bless anyone else and that upsets him.
2 – Where he wants the blessing to be taken away from someone else because he wants it, in the hope that it will come to him.
3 – Where he wishes for himself a blessing like that which someone else has, without wanting it to be taken away from the other person. This is permissible and is not called hasad rather it is called ghibtah.
The envier harms himself in three ways:
1 – He earns sin because hasad is haraam.
2 – It is bad etiquette before Allaah, because what hasad really means is hating Allaah’s blessing His slaves, and objecting to what Allaah does.
3 – He suffers because of too much worry and distress.
The above Taken from Hasad – Envy – Majmoo’ Fataawa al-Lajnah al-Daa’imah