What are the great sins according to the Prophet Muhammad (saw)?
 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."