The Meaning of Hasad :  To desire the destruction or loss of something good which belongs to someone else.  This is different from to desire it for oneself but without desiring its loss or destruction from the one who has it.  This latter meaning is called Al-Ghabta. Allah mentions in the Qur'an the envy of the disbelievers, the hypocrites and of the people generally. Allah said about the disbelievers:

{Many of the People of the Book wish that they could turn you back into disbelievers after you have believed out of envy in their hearts even after the truth has become clear to them.  So, forgive and forbear until Allah brings His order.  Allah is surely in control of all things.} Al-Baqarah: 109

{..after the trugh has become clear to them...} - even after it became clear to them that Muhammad (sas) was the Messenger of Allah.  For whatever weakness or reason, they were unwilling to submit to the truth although they recognized it and this made them envious and hostile toward those who had submitted.   This is their reality in all times and places: the closer they get to "understanding" (i.e., knowing that this message is the truth), the more violent their hatred toward the believers becomes.  Umar (ra) was most dangerous to the Muslims right before he became Muslim.  That is also why the hatred of the Arab disbelievers and other who live amongst Muslims but who have not accepted the truth is more violent than disbelieving peoples who live far from them.

{...forgive and forbear...}  The first word i'foo means to not raise complaints against them for their transgressions.  The second word isfahoo means to remove the effect of their transgression from your hearts.

{...until Allah brings His order...} Until the order of Allah results in the killing of those who fight the believers, the expulsion of whoever Allah wills, the payment of jizya by others and the embracing of Islam by many others.  Fighting had not yet been permitted to the Muslims to defend themselves and the da'wah of Islam, so they only had to be patient in the face of persecution.

After mentioning the disbelief of the Jews and their saying that the mushrikoon of Arabia were closer to guidance than Muhammad (sas) and those with him, Allah says:

{Or do you envy the people for the favor which Allah has given them?  We have given the people of Ibrahim the Book and the Wisdom and we gave them a magnificent dominion.} An-Nisaa: 54

Allah granted the Muslims prophethood, a new book and power and victory over their enemies.  Before the Messengership of Muhammad (sas), the Jews would sometimes fight with the Arab tribes of Yathrib (Madina).  If they encountered a setback in battle, they used to threaten them saying that when the prophet-king arrives, they will vanquish them with him at their side.  This is because they knew of the coming prophet, that he would come in that area and that his time was near.  What they didn't know was that he would come not among the Children of Israel, but among their cousins, the Arabs.  It is said that their book spoke of the prophet-king coming among their "cousins" and they failed to understand the import of the word.  When in fact the prophet-king arrived among their enemies, the Arabs, most of them refused to accept the new message though they knew it to be the truth.

{...we have given the people of Ibrahim...}  Here Allah reminds them that this is nothing new.  Rather, it is the way of Allah, to grant such things to his messengers.
Speaking about the hypocrites (those among the Muslims whose outer appearance is belief and practice but whose inner reality is kufr and rebellion) and after mentioning their attempts to be excused from jihad with phony excuses, Allah says:

{If something good befalls you, it irritates them but if something bad befalls you, they say: We indeed took our precautions in time!  And they turn away, rejoicing.} At-Tauba: 50
{...something good befalls you...}

i.e., victory in battle and spoils of war.  In such case, if present, they will be the first to claim the spoils and to complain if they don't feel they got enough.  If they begged out of the battle, they will be consumed with envy that others got the goods.  On the other hand, when the Muslims suffer a setback, they rejoice that they were not present to be killed or injured just as they rejoice in the suffering of the Muslims.  So the hypocrites (whose inner reality is kufr) envy the belief of the believers just as their brothers ther Jews, Christians and other disbelievers envy them.  This is explained further in the following verse:

{Those who dropped out will say, when you come upon much spoils of war and are about to take it: Allow us to go with you.  They wish to change the Word of Allah.  Say: You will not follow us.  This Allah has already said.   Then, they will say:  You are just envious of us.  Rather, they are almost completely incapable of understanding.} Al-Fath: 15

The story behind this verse is that when Muhammad (sas) and those with him returned from Al-Hudaibiya, Allah promised them, Allah promised them victory at Khaibar and dedicated the spoils from Khaibar to those who participated in Al-Hudaibiya exclusively.  When the hypocrites knew of this, they as the Prophet (sas) if they, too, could participate in Khaibar because of their desire for the promised spoils.   That is why Allah said {...They wish to change the Word of Allah...}.

{...they are almost completely incapable of understanding...}   Or, it could be translated: {...they do not understand except very little...}  Their understanding is limited to this world and to their desire for its things and riches.  As for fighting to make the word of Allah uppermost in the earth and sacrificing in the cause of Allah, that is beyond their understanding.
Allah taught us to seek refuge in Him from envy and from those who envy in Sura Al-Falaq:

{Say: I seek refuge in the Lord of the splitting (or dawn).   From the evil among His creation.  And from the evil of darkness when it falls.  And from the evil of those who blow incantations over knots.  And from the envious one when he envies.} Al-Falaq

Al-Hasad appears to be the worst of the evils mentioned and Allah mentions them in ascending order.  It is the most destructive to the relationships between Muslims and if Muslims do not have good relations between themselves, they will be incapable of accomplishing any of Allah's orders and they will become weak and be overcome, slaughtered, exiled and oppressed by their enemies and Allah's enemies.

The Prophet (sas) said: "Do not hate one another and do not envy one another and do not turn your backs on one another.  Be slaves of Allah and brothers.  It is not allowed for a Muslim to avoid his brother for more than three days." Muslim & Bukhari

Being "brothers" follows from being "slaves of Allah".   If we are truly slaves of Allah, then brotherhood will come naturally because of our piety and our remembrance of the rights of others and our obligations toward them.   If we find that we are lacking in brotherhood, then by definition, we are lacking in our slavery to Allah.  There is weakness in our belief/practice which has afflicted the relations of brotherhood between us.

And: "Do not envy one another, do not defraud one another, do not despise one another, do not turn your backs on one another and let none of you make an offer over the [unconcluded] offer of his brother.  Be slaves of Allah and brothers.   Every Muslim is a brother to every Muslim.  He does not oppress him, nor betray him, nor deceive him, nor despise him.  Taqwa is right here.  (He (sas) pointed to his heart and said that three times.)  It is sufficient evil for a Muslim to look down on his brother Muslim.  Every Muslim is sacred to every other Muslim - his blood, his property and his self-esteem." Muslim

Islam covers all aspects of life.  It is not enough to claim to be a brother to all Muslims and then cheat them in business or deceive them in any way.   Our loyalty must always be to the Muslims above and before all others.  Our loyalty to each and every individual must be to the degree of their obedience to Allah and His Messenger (sas).

And: "The diseases of the nations who came before you will creep into your nation: envy and hatred.  By the One in whose Hand the soul of Muhammad is, you have not believed until you love one another.  Should I not tell you about something which, if you do it, you will love one another?  Spread the greeting [of peace] among you."