Since we're on the topic, here's a few hadiths regarding cheating.
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).
Muslim (102) also narrated from Abu Hurayrah (may Allaah be pleased with him) that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “Whoever cheats (or deceives) does not belong to me.”
and an article for more information:
Islam QA