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.”
Sahih Bukhari, Volume 3, Book48, Number 821