What is Hasad?
Hasad (jealousy) is defined as: تمني زوال نعمة الغير (the desire or wish for the deprivation of a bounty from another). When Allah Ta’ala has blessed a person with His bounties such as wealth, honour etc. then a jealous person feels a burning desire in his heart for that person to be deprived of those blessings.
However, if one has a desire to also have these comforts and blessings, but does not wish for these blessings to be taken away from the other person, then if it is for some worldly reason, it is known as Ghibtah (envy). On the other hand, if it is for a religious reason then it is known as Tanaafus (to compete).
With regards to the ruling of each in Shariah: Hasad is Haram, Ghibtah is permissible and Tanaafus is Waajib (compulsory).
As Muslims we believe that everything happens by the will of Allah Ta’ala. Allah Ta’ala gives to whomsoever He wills in whatever quantity He wills. One should not question why Allah Ta’ala has blessed some more than others. There is always the bigger picture that we are often unable to perceive. It is essential that we place our trust in Allah Ta’ala, fully realizing that there is wisdom in His decisions and that whatever He decides is the best for us.
أَهُمْ يَقْسِمُونَ رَحْمَتَ رَبِّكَ ۚ نَحْنُ قَسَمْنَا بَيْنَهُم مَّعِيشَتَهُمْ فِي الْحَيَاةِ الدُّنْيَا ۚ وَرَفَعْنَا بَعْضَهُمْ فَوْقَ بَعْضٍ دَرَجَاتٍ لِّيَتَّخِذَ بَعْضُهُم بَعْضًا سُخْرِيًّا ۗ وَرَحْمَتُ رَبِّكَ خَيْرٌ مِّمَّا يَجْمَعُونَ – 43:32
Translation: Do they distribute the mercy of your Lord? It is We who have apportioned among them their livelihood in the life of this world and have raised some of them above others in degrees [of rank] that they may make use of one another for service. But the mercy of your Lord is better than whatever they accumulate. (43:32)
When Allah Ta’ala gives more to someone then we simply have to accept that. A jealous person is actually fighting with Allah Ta’ala. Allah Ta’ala says:
أَمْ يَحْسُدُونَ النَّاسَ عَلَىٰ مَا آتَاهُمُ اللَّهُ مِن فَضْلِهِ ۖ فَقَدْ آتَيْنَا آلَ إِبْرَاهِيمَ الْكِتَابَ وَالْحِكْمَةَ وَآتَيْنَاهُم مُّلْكًا عَظِيمًا – 4:54
Translation: Do they envy others for the bounty that Allah has bestowed upon them? (Let them bear in mind that) We bestowed upon the house of Abraham the Book and Wisdom, and We bestowed upon them a mighty dominion. (4:54)
In the above verse Allah Ta’ala is posing a question to the jealous person that when Allah has given His bounties to someone are you going to make Hasad?
When a person does good deeds then Nur is created in his heart, but when he starts becoming jealous of others, then all of that Nur gets devoured by this jealousy. Rasulullah (Sallallahu Alayhi Wasallam) has warned us:
عَنْ أَبِي هُرَيْرَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ ” إِيَّاكُمْ وَالْحَسَدَ فَإِنَّ الْحَسَدَ يَأْكُلُ الْحَسَنَاتِ كَمَا تَأْكُلُ النَّارُ الْحَطَبَ ” (سنن ابي داود-4903)
Translation: Abu Hurayrah narrates:
The Prophet (Sallallahu Alayhi Wasallam) said: “Avoid envy, for envy devours good deeds just as fire devours firewood.” (Sunan Abi Dawud-4903)
What leads to Hasad?
1. When a person is not content with the will and decree of Allah Ta’ala.
2. When a person has enmity for someone.
3. When a person in the same profession as you is better off.
The harms of Hasad:
You should understand that wishing bad for others will not harm them in any way. Rather it will only affect you negatively in the following ways:
1. One becomes deprived from the happiness of Allah. If a person has gained the pleasure of everyone but not of Allah, then he has nothing.
2. Resenting one whom Allah Ta’ala bestowed His blessings upon shows dissatisfaction with Taqdeer (the will and decree of Allah Ta’ala). Taqdeer is the belief that all things, past, present and future occur in accordance with the knowledge, will and command of Allah Ta’ala. Belief in Taqdeer is a fundamental tenet of Imaan.
3. It will only increase one in despair. When a person has Hasad, his full concentration is on someone else’s life, in which, by doing so, harms himself and his own happiness.
The cure for Hasad:
The following steps can be implemented to rid oneself of jealousy:
1. First, one should make Istighfar (seek forgiveness) from Allah Ta’ala and make dua to Him to grant the ability to make Tawbah and rid him of such feelings.
2. Never practice on the dictates of Hasad. If you find yourself having ill feelings towards an individual, make dua for him. This will dispel such feelings from you. Make dua for that person to be even more blessed than he already is.
3. We also advise that you look towards the people who are less fortunate than you are. Do not look at those who possess more than you. You should also bear in mind that having a lot of wealth and possessions does not guarantee happiness. Often, some extremely wealthy people despite it seeming that they have everything, actually lack inner peace and are often depressed. Rasulullah (sallallahu alayhi wasalllam) taught us how to deal with such trials:
عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ” انْظُرُوا إِلَى مَنْ أَسْفَلَ مِنْكُمْ وَلاَ تَنْظُرُوا إِلَى مَنْ هُوَ فَوْقَكُمْ فَهُوَ أَجْدَرُ أَنْ لاَ تَزْدَرُوا
نِعْمَةَ اللَّهِ ” .(صحيح مسلم-2963)
Translation: Abu Huraira reported Allah’s Messenger (Sallallahu Alayhi Wasalllam) as saying:“Look towards those who are below you, not towards those who are above you, for indeed, that is more conducive to your not belittling the blessing of Allah upon you.” (Sahih Muslim-2963)
This is an immense wisdom that we should hold firmly onto. We need to reflect on
the situation of those who are less fortunate than us. You should consider visiting those around you who are less fortunate. 
You also inquire how to be more grateful to Allah.
One way to be grateful is by simply making Shukr (being grateful) to Allah Ta’ala for what He has given to you. Allah Ta’ala says:
وَإِذْ تَأَذَّنَ رَبُّكُمْ لَئِن شَكَرْتُمْ لَأَزِيدَنَّكُمْ ۖ وَلَئِن كَفَرْتُمْ إِنَّ عَذَابِي لَشَدِيدٌ – (14:7)
Translation: And [remember] when your Lord proclaimed, ‘If you are grateful, I will surely increase you [in favor]; but if you deny, indeed, My punishment is severe.’ (14:7)
Shukr (gratefulness) can be made in three ways:
Heart: In your heart, concentrate on the blessings Allah has bestowed on you, and recognize that Allah alone is the One Who has bestowed such great blessings.
Tongue: Use your tongue to acknowledge verbally – after believing in the heart- that the One who gives blessings is Allah. In addition, keep your tongue busy with praise of Allah.
Physical abilities: Use the physical abilities that you have been granted in the obedience of Allah and prevent them from committing sins and acts of disobedience.
And Allah Ta’āla Knows Best
Checked and Approved by,
Mufti Ebrahim Desai.
الوابل الصيب من الكلم الطيب (ص: 5) 
فإن العبد دائم التقلب بين هذه الأطباق الثلاث
الأول: نعم من الله تعالى تترادف عليه، فقيدها (الشكر) وهو مبني على ثلاثة أركان: الاعتراف بها باطناً، والتحدث بها ظاهراً، وتصريفها في مرضاة وليها ومسديها ومعطيها
فإذا فعل ذلك فقد شكرها مع تقصيره في شكرها
الحلل المتاحة في توثيق وتخريج نصوص الدرر المباحة (ص-376)
الخامس عشر: الحسد ، وهو: إرادة زوال نعمة الله تعالى (من علم أو جاه أو عمل أو عافية) عن أحد ممّا له فيه (أي في ذلك الأمر ) صلاح ديني أو دنيوي ، من غير ضرر (في ذلك الأمر ، يلحق ذلك الأحد) في الآخرة ، أو عدم ( إرادة ) وصولها إليه ، وحبه من غير إنكار له، ولو وقع في قلبك – من غير اختيار ، ووجدت الإنكار لوقوعه فيه ـ فلا بأس به بالاتفاق…
وعلاجه العلمي: أن تعلم أنّ الحسد ضرر عليك في الدنيا والدين ، وأنه لا ضرر فيه على المحسود فيهما (أي في الدنيا والدين ) ، بل ينتفع به فيهما . أما ضرره لك في الدين : فلأنّك بالحسد سخطت قضاء الله تعالى ، وكرهت نعمته التي قسمها لعباده ، وعدله ( عز وجل فيك حيث منعك ما لا تستحقه ) واستنكرت ذلك ، وغششت رجلا من المؤمنين وتركت نصحه ، والغش حرام ، والنصيحةً واجبة. وأما ضرره لك في الدنيا : فغمّ و حزن ، وضيق نفس…
وعلاجه العملي: أن يكلف نفسه نقيض مقتضاه ، فإن بعثه الحسد على القدح فيه ، كلف لسانه المدح له ، (وإن بعثه على التكبر عليه ، ألزم نفسه التواضع له والاعتذار إليه ) وإن على كف الإنعام عليه ، ألزم نفسه الزيادة في الإنعام ، وإن على الدعاء عليه ، دعا له بزيادة النعمة التي حسده فيها