Narrated Anas: The Prophet was asked about the great sins He said, “They are:– (1 ) To join others in worship with Allah, (2) To be undutiful to one’s parents. (3) To kill a person (which Allah has forbidden to kill) (i.e. to commit the crime of murdering). (4) And to give a false witness.” {Volume 3, Book 48, Number 821 : Sahih Bukhari}