It was narrated that 'Abdullah said:"I said: 'O Messenger of Allah, which sin is the most grievous?' He said: 'Setting up a rival to Allah while it is He that has created you.' I said: 'Then what?' He said: 'Killing your child for fear that he may eat with you.' I said: 'Then what?' He said: 'Committing adultery with your neighbor's wife

English translation · Sunan an-Nasa'i