Allah, Most High, has said: "From the evil of the envier when he envies," [Al-Qur'an 113:5] and: "Are they jealous of people because of what Allah in His bounty has given them?" [Al-Qur'an 4:54]
Bukhari relates on the authority of Anas that the Prophet, sallallahu 'alayhi wa sallam, said:"Do not hate one another, or envy one another, or turn your backs on one another; rather be brethren as Allah's slaves. It is not lawful for a Muslim to break off relations with his brother for more than three consecutive nights so that they both turn from each other: the better of them is he who gives the first greeting."
Al-Hasan al-Basri said with regard to Allah's statement, "From the evil of the envier when he envies": "This was the first sin to have been committed in heaven." (A reference to Satan's jealousy of Adam, 'alayhis-salam.)
Al-Ahnaf ibn Qays said, "Mark these five truths: an envious man finds no peace, a liar has no manly virtue, a greedy man is not to be trusted, a miser has no power, and a man of bad character has no glory."
Khalil ibn Ahmad said, "A man who does wrong through envy is very similar to one who is wronged: he has no peace of mind, and he is always grieved."
Al-Mubarrad recited the following lines:
The eye of the envier always sees scandal,
bringing out faults and hiding the good.
He meets you cheerfully, with a smiling face,
while his heart conceals his true feelings.
The envier enmity comes without provocation,
yet he accepts no excuses while he attacks.