Narrated `Abdullah: I or somebody, asked Allah's Messenger Which is the biggest sin in the Sight of Allah? He said, That you set up a rival (in worship) to Allah though He Alone created you. I asked, What is next? He said, Then, that you kill your son, being afraid that he may share your meals with you. I asked, What is next? He said, That you commit illegal sexual intercourse with the wife of your neighbor. Then the following Verse was revealed to confirm the statement of Allah's Messenger : Those who invoke not with Allah, any other god, nor kill life as Allah has forbidden except for just cause, nor commit illegal sexual intercourse. (25.68)