Qur'an, Al-A'la, Surah 87:7-10
We shall enlighten you with our revelations in a manner that you will not forget, save that which Allah may will. Behold, We are aware of all that is hidden and that which is manifest, and We will guide you to the easiest path. Therefore admonish others whether this admonition avails or not. Those who fear the Lord will pay heed.