Taken from
http://www.islamqa.com/en/ref/22845The phenomenon of cheatingThe phenomenon of cheating is widespread in society. What is the attitude of Islam towards this phenomenon?In the Qur’aan, Allaah has condemned cheating and the people who do it, and has warned them of bad consequences. This may be understood from the words (interpretation of the meaning):
“Woe to Al‑Mutaffifoon (those who give less in measure and weight).
Those who, when they have to receive by measure from men, demand full measure,
And when they have to give by measure or weight to (other) men, give less than due”
[al-Mutaffifeen 83:1]
This is a severe warning to those who cheat (by giving less) in weights and measures, so how about those who steal, embezzle and withhold from the people the things that are their due? These are more deserving of the warning than those who cheat in weights and measures.
The Prophet of Allaah Shu’ayb warned his people against reducing the value of people’s property and cheating in weights and measures, as Allaah has told us in the Qur’aan.
Similarly the Prophet SAWS (peace and blessings of Allaah be upon him) cautioned us against cheating and issued a warning to the one who does this. The Prophet SAWS (peace and blessings of Allaah be upon him) passed by a pile of food and put his hand into it, and his fingers touched something wet. He said, “What is this, O seller of the food?” The man said, “It got rained on, O Messenger of Allaah.” He said, “Why did you not put it (the wet part) on top of the pile so that the people could see it? He who deceives does not belong to me.” According to other reports, “He who deceives us is not one of us,” or, “He is not one of us who deceives us.” (Narrated by Muslim).
The wording of the version narrated by al-Nawawi, “he is not one of us”, is sufficient warning against cheating and sufficient deterrent against indulging in this heinous sin.
We need desperately to instill this message in our hearts so that we might stir the conscience and be aware that Allaah is watching all that we do, without the need for any human supervisor.
The way we deal with this phenomenon and other destructive phenomena that exist in society should not be like a patient who has a problem in his appendix and needs surgery, but instead they heat up a poultice for him and put it on that spot to relieve the pain… for then the patient will die before they even think of calling the doctor.
Here we will examine the phenomenon of cheating, now that you know the warnings that apply to it.
Definition of cheating:
...
Read more on http://www.islamqa.com/en/ref/22845