‘Abdallah b. Mas'ud said that a man asked God’s messenger, what was the greatest sin in God’s sight, to which he replied,“That you should treat anything as equal to God when He has created you."“What next?” he asked, to which he replied,“That you should kill your child for fear that he may eat along with you.”. “What next?" he asked, to which he replied,“That you should commit adultery with your neighbour’s wife." God has revealed words which verify this:“Those who do not invoke another god along with God, or kill one whom God has declared inviolate without a just cause, or commit fornication..." (Bukhari and Muslim.)