Sahih Bukhari(volume 3, Book 48, Number 821):
Narrated by Anas: The Prophet(Sallalahu Alaihi Wasallam) 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."
Aaj kal log yeh sab kam kartay
Jazak Allah Khair
Shirk kabira gunah hay jis ki mafi nahi..
or aj kal log sub sey zydah shirk karty hain..
qabroon per ja kar mangty hain etc etc..