Commentary
The word: غَرُورُ (gharur) is an emphatic form of an adjective that means one who is very deceiving (hence, rendered here as 'big deceiver' ). It refers to the Shaitan (Satan) whose sole job is to deceive people and throw them into disbelief and sin. And the expression لَا يَغُرَّنَّكُم بِاللَّـهِ الْغَرُورُ (5) means 'nor should you be deceived about Allah'. To explain this deception, it can be said that the Shaitan may not, by showing your evil deeds as good, cause you to become so involved with these that you reach the stage when you go on committing a sin and, at the same time, keep thinking that you are of those accepted in the sight of Allah, and that you will not have to undergo any punishment.' (Qurtubi)