Terminologically, injustice is to put a thing in an inappropriate place. Polytheism, hence, is grave injustice, because it is replaced with monotheism. Conventionally, injustice stands for the seizure of rights, and the words and deeds of hostility against others, such as revilement, backbiting, and confiscation of property, crimes of beating or murder, and the like forms of wrongdoings.  Injustice, however, is one of the bad characteristics that are deep-rooted in most of the mentalities. All over history, humankind suffered various kinds of tragedies that made life seem depressing. It therefore is the comprehensive of sins, source of evils, and incentive of corruption. God says:

The unjust will certainly have no happiness.

Allah does not guide the unjust.

Allah does not love the unjust.

The unjust will face a painful punishment.

We destroyed certain generations who lived before you because of their injustice.

Do not think that Allah is unaware of what the unjust people do.

(On the Day of Judgment) to redeem oneself of one's injustice, one would gladly spend the wealth of the whole earth if it were possible. On seeing, the torment one will try to hide his regret. They will all be judged fairly and no wrong will be done to them.

Amir ul-Mu'minin (PBUH) said: By Allah, even if I am given all the domains of the seven (stars) with all that exists under the skies in order that I may disobey Allah to the extent of snatching one grain of barley from an ant, I would not do it. For me, your world is lighter than the leaf in the mouth of a locust that is chewing it. What has Ali to do with bounties that will pass away and pleasures that will not last?

Abu Bassir narrated the following:

Two parties of litigation filed their case before Imam as-Sadiq (PBUH). After he had listened to both of them, the Imam spoke: It is quite true that he who seizes something by wrong means is not seizing goodness. Certainly, the oppressed party seizes from the religion of the wronging party more than that which the wronging party seizes from the oppressed party’s property. He who does evil to people should not show loathing towards the evil that is done to him. As a matter of fact, man will harvest nothing but that which he sowed. No one will harvest sweetness from the bitter, and no one will harvest bitterness from the sweet.

These words of the Imam (PBUH) made the two parties settle their litigation before they left him. Imam as-Sadiq (PBUH) said: He who seizes his brother’s property wrongfully will consume a flame of fire on the Day of Resurrection. As for him who wrongs others, Allah will cause him, his descendants, or the descendants of his descendants to be wronged by absolute persons.

When the Imam was asked how it is acceptable for God to cause somebody to wrong the descendants of the wrongdoer, he referred to Gods saying: Those who are concerned about the welfare of their own children after their death should have fear of Allah and guide them properly.

To punish sons for their fathers crimes is restricted only to those who accept and welcome their fathers wrongdoings so that they would inherit such usurped properties. To punish such sons is a reproach that discourages the wrongdoers from aggressions out of their care for their dear sons. It is also a good tiding for the oppressed individuals that their oppressors will be punished eventually. The Prophet (s) said: For anyone who begins his day without having the intent to oppress anybody, Allah will forgive his sins “that he committed against his Lord.