Ibn Mas'ud (RAA) narrated, ‘l asked the Messenger of Allah (ﷺ) “Which sin is the most serious?” He replied, attribute a partner to Allah, though He Alone has created you. “I asked, “What next?” He said, kill your child, fearing that he will share your food with you.” I asked again, “What next?” He said, “To commit adultery with your neighbor’s wife.” Agreed upon.