Abu Hurairah (RA) narrates that Rasulullah (peace be upon him) happened to pass by a heap of grain and inserted his hand into it; his fingers were moistened by the wet grain. At this, he asked the owner of the grain: What is this? The man replied: O Rasulullah! It is due to rain. Rasulullah (peace be upon him) said: Why didn't you put the damp (wet) grain on top of the heap, so people could see it? He who deceives people does not belong to me (my Ummah).
Source: Sahih Muslim.
We should always remember that deception is one of the qualities of Shaitan. Others may not see us when we are deceiving them but Allah is there watching us. A true believer knowing that he has to stand in front of Allah will avoid such activities.