And the statement of Allah, the Exalted (in Surah Ha Mim Sajdah): "You associate partners with Him, while He is the Owner of all the worlds." The statement of Allah: "And those who do not call upon any other deity along with Allah (Surah Al-Furqan)." "And indeed, it has been revealed to you and to those before you that if you associate partners (with Allah), your deeds will surely become worthless and you will surely be among the losers (Surah Az-Zumar)." And ‘Ikrimah said, the meaning of «وما يؤمن أكثرهم بالله إلا وهم مشركون» is: "If you ask them who created the heavens and the earth, they will answer: Allah. This is their faith, but they worship others besides Allah." And in this chapter, it is also explained that the actions of the servant, their acquisition, all are created by Allah, because Allah said (in Surah Al-Furqan): "It is that Lord who created everything, then determined it with due proportion." And Mujahid said that (in Surah Al-Hajj) the meaning of «ما تنزل الملائكة إلا بالحق» is: "The angels descend with Allah’s message and His punishment." And (in Surah Al-Ahzab) it is said: "That He may question the truthful about their truthfulness," meaning the prophets who conveyed Allah’s command. And (in Surah Al-Hijr) it is said: "We are the guardians of the Qur’an." Mujahid said: "That is, with Us." And (in Surah Az-Zumar) it is said: "And he who brought the truth," meaning the Qur’an, "and he who confirmed it," meaning the believer who, on the Day of Resurrection, will say to his Lord: "You gave me the Qur’an, and I acted upon it."

Narrated `Abdullah: I asked Allah's Apostle "What is the biggest sin in the sight of Allah?" He said, "To set up rivals unto Allah though He alone created you." I said, "In fact, that is a tremendous sin," and added, "What next?" He said, "To kill your son being afraid that he may share your food with you." I further asked, "What next?" He said, "To commit illegal sexual intercourse with the wife of your neighbor."