The Book of Allah (Quran): In it exist, the History of the ones before you, the Knowledge of the ones after you, the Judgment of the matters amongst you.
It is the Precise Judgment. Separates the Truth from false.
It is not humor.
Whoever abandons It with arrogance, Allah smashes him.
Whoever seeks guidance apart from It, Allah leads him astray.
It is the Firm Bond with Allah.
It is the Supreme Reminder.
It is the Straightest Path.
It is such that the sense-desires cannot divert It and the tongues cannot confuse It. The scholars never get satiated with It. Repetition of It does not weary and the wonders of It never get exhausted.
It is such a Book that when the jinns listened to It, they couldn't resist saying: "We have indeed heard a wonderful Qur’an which guides to the Right Way; so we have believed in it. We never associate anyone else with our Lord."
Whoever talks based on It, speaks the Truth, whoever lives according to It, gets rewarded and whoever judges by It, judges justly, whoever invites to It, guides to the Right Path.
Source: Tirmidhi, Hadith no: 2906, Al-Harith from Ali and Ali from The Messenger of Allah (pbu).