Hasad is such a dangerous characteristic that Allah revealed verses of the Quran to be recited as a protection from the jealous,

Say: “I seek refuge with (Allah) the Lord of the daybreak, (113:1)
“From the evil of what He has created; (113:2)
“And from the evil of the darkening (night) as it comes with its darkness; (or the moon as it sets or goes away). (113:3)
“And from the evil of the witchcrafts when they blow in the knots, (113:4)
“And from the evil of the envier when he envies.” (113:5)

“Beware of jealousy, for verily it destroys good deeds the way fire destroys wood.”

Hasad (jealousy and envy) is among the most destructive emotions or feeling which a man may have towards his fellow human being. It causes him to wish evil for others and to be happy when misfortune befalls them. The Prophet (sallallahu alaihi wa-sallam) warned against envy by comparing it to fire that completely burns wood. He (sallallahu alaihi wa-sallam) said: “Beware of jealousy, for verily it destroys good deeds the way fire destroys wood.” [Abu Dawood]

Hasad is a disease of the heart and it causes impurity to the heart, when Allah’s Messenger (sallallahu alaihi wa-sallam) was asked who are the best of people? He (sallallahu alaihi wa-sallam) replied: “the one with a clean heart and truthful tongue.” They asked: ‘We understand a truthful tongue, but what does a “clean heart” mean?’ he answered: ‘It is the heart of one that is pious, pure, and is free of sin, transgressions, hatred and Hasad.” [Ibn Majah]

At-Tirmidhee narrated from al-Zubayr Ibn al-Awam that the Prophet (sallallahu alaihi wa-sallam) said: “There has come to you the disease of the nations before you, jealousy and hatred. This is the ‘shaver’ (destroyer); I do not say that it shaves hair, but that it shaves (destroys) faith?” [(Hasan) Jamee at-Tirmidhee (2434)]

Hasad can cause the person to indulge in disbelief because it causes the individual to feel that Allah has not been fair with him; he forgets all the mercy and blessings, which Allah has bestowed upon him. The Messenger of Allah (sallallahu alaihi wa-sallam) said: “They are enemies for Allah’s bounties.” They asked: “Who are they?” He said: “Those who envy people for what Allah has given them of Bounty.” [At-Tabaranee]

Allah through His Absolute Wisdom has given some people more wealth, intelligence, beauty, strength, children, etc. than others. The believing Muslim should be content with what Allah has destined for him. Allah says: And Allah has preferred some of you above others in wealth and properties. Then, those who are preferred will by no means hand over their wealth and properties to those (slaves) whom their right hands possess, so that they may be equal with them in respect thereof. Do they then deny the Favor of Allah? (16:71]

Or do they envy men (Muhammad SAW and his followers) for what Allah has given them of His Bounty? Then We had already given the family of Ibrahim (Abraham) the Book and Al­Hikmah (As­Sunnah – Divine Inspiration to those Prophets not written in the form of a book), and conferred upon them a great kingdom. (4:54]

Is it they who would portion out the Mercy of your Lord? It is We Who portion out between them their livelihood in this world, and We raised some of them above others in ranks, so that some may employ others in their work. But the Mercy (Paradise) of your Lord (O Muhammad SAW) is better than the (wealth of this world) which they amass. (43:32)

Meaning the mercy of Allah is better than the convenience of the world. The materials of this life do not make one superior to another in Allah’s Judgment. True superiority lies in Taqwa (righteousness, fear of Allah). He said: O mankind! We have created you from a male and a female, and made you into nations and tribes, that you may know one another. Verily, the most honorable of you with Allah is that (believer) who has At-Taqwa [i.e. one of the Muttaq’n (pious – see V.2:2). Verily, Allah is All-Knowing, All-Aware. (49:13)

And adornments of gold. Yet all this (i.e. the roofs, doors, stairs, elevators, thrones etc. of their houses) would have been nothing but an enjoyment of this world. And the Hereafter with your Lord is only for the Muttaq’n. (43:35)

What belongs to the transient world is of no significance before Allah. The Prophet (sallallahu alaihi wa-sallam) said: “If this world were worth a mosquito’s wing before Allah, He would not give a disbeliever a drink of water.” [At-Tirmidhee]

The favors of Allah in the world are a test; the more the favors, the more the tests. Al-Hasan al-Basri said: “Umar Ibn Khattab wrote this letter to Abu Musa al-Ash’ari, ‘Be content with your provision in this world, for the Most Merciful has honored some of His servants over others in terms of provision as a test of both. The one who has been given plenty is being tested to see if he will give thanks to Allah and fulfill the duties which are his by virtue of his wealth?” [Ibn Hatim]

Allah, the Exalted, has therefore forbidden us from desiring what other shave,
And wish not for the things in which Allah has made some of you to excel others. For men there is reward for what they have earned, (and likewise) for women there is reward for what they have earned, and ask Allah of His Bounty. Surely, Allah is Ever All­ Knower of everything. (4:32)

In order to discourage envy, the Prophet (sallallahu alaihi wa-sallam) said: “Do not look to those above you. Look to those below you, as it will more likely remind you of Allah’s favors bestowed on you.” [Saheeh al-Bukharee and Saheeh Muslim] On another occasion, he said: “If one of you looks at someone wealthier and better built than him, he should also look at someone of lower standard than himself.” [Saheeh Muslim]