Al-Anfal (53): Allah will never change the blessing which has bestowed upon a people unless they change what is in themselves; and verily Allah is the Knowing Hearer.
In different hadiths, such factors as injustice and sin has been said to change the blessings bestowed upon peopla by Allah, as seeking forgiveness from Allah for one's sins and stop commiting sins as well as moving in the way Allah results in receiving different kinds of blessings from Allah in large quantities.
To commit Sins and exercise oppressions will keep one away from the grace of Allad, as Imam Ali (A.S) mentioned it in his Qasi sermon. We sldo read in Kumayl Prayer:
اللهم اغفرلی الذنوب الّتی تهتک العصم... اللهم اغفرلی الذنوب الّتی تغیّر النّعم...»
Oh my Lord! Forgive me for those sins which break my veil of purity; Oh my Lord! Forgive me for those sins which changes the blessings which you have bestowed upon me...
A letter from Imam Ali (A.S) to his commander in chief, Malik-al–Ashtar reads:" Nothing alters Allah's blessings as much as cruelty and injustice, because Allah hears the cries of the oppressed and is ever watchful of the oppressors".
Imam Sadiq (A.S) said in this regard:"always seek refuge in Allah for your daily difficulties and problems which are the punishment for your sins".
Abu Khalid Kabuli says: I heard from Imam Sajjad (A.S) saying: "sins that result in the change of the blessings, include cruelty to people, abandoning good works, stop helping people, misusing the blessings, and quitting gratitude and appreciation. Allah the Almighty says: "Allah changes not the condition of a folk until they (first) change what id in their hearts" (Al-ra'd 11).
And the sins that incur the wrath of Allah include the oppression being deliberatly exercised by ab oppressor, trangressing people's rights and deriding them. There are also Sins that keep one's ailment away; these include expressing poverty, being asleep at the time of the Salat al-Isha until the time for saying the parayer is passed and so is the Morning Prayer, underestimating the blessings, and complaining Allah. But the sins that lead into losing one's purity and put one's face in danger include: drinking wine, gambling, making fun of people, expressing useless words, find faulting with people and accompanying evil men".
And also stated: "sins that bring about punishments include not helping the oppressed, not supporting the poor, and stop enjoining what is good and stop forbidding what is wrong. Sins that help the enemies dominate human beings are: apparent injustice, public sin, committing unlawful deeds, disobedience of the righteous and following the miscreants. Sins that quickly destroy human beings include: stop visiting one's close family, false oath, unrealistic remarks, commiting adultery, hindering the Muslims from acheiving their goals, and claiming leadership without merit. Sins that destroy one's hope are: despair of the Mercy of Allah, despair of Allah, not trusting in Allah and denying the promises of Allah. And finally the sins that prevent the acceptance of prayers include: grudging, inner malice, hypocrisy to others, rejecting others demands for help, delaying the obligatory prayers until the time for performing them is passed, not to perform good deeds for people for the sake of Allah, not giving alms and abandoning charity, insulting people."