Narrated 'Abdullah: I asked the Prophet, "What is the greatest sin in the Sight of Allah?" He said, "That you set up a rival unto Allah though He Alone created you". I said, "That is indeed a great sin". Then asked, "What is next?" He said, "To kill your son lest he should share your food with you". I asked, "What is next?" He said, "To commit illegal sexual intercourse with the wife of your neighbor".
The hadith also teaches us about how important it is for us to respect our parents and not do anything which would hurt them or make them unhappy. It also reminds us about how important it is for us to stay away from any kind of immoral behavior such as adultery which can have serious consequences both in this life and hereafter if we don't repent from it soon enough.
