Surat Al Isra' (81-82)

{وَقُلْ جَاء الْحَقُّ وَزَهَقَ الْبَاطِلُ إِنَّ الْبَاطِلَ كَانَ زَهُوقاً} (الإسراء : 81)

81- O Messenger, say: True Islam and the great Shari`ah have come and polytheism and disbelief were removed, so there is no idol worship after that day and there is no stability and firmness to falsehood in the presence of the truth.

{وَنُنَزِّلُ مِنَ الْقُرْآنِ مَا هُوَ شِفَاء وَرَحْمَةٌ لِّلْمُؤْمِنِينَ وَلاَ يَزِيدُ الظَّالِمِينَ إَلاَّ خَسَاراً} (الإسراء : 82)

82- We reveal down from the Qur'an cures and treatments to the diseases of oneself and the heart such as: Error, ignorance, satanic insinuations, doubt, deviation, worry, whims, and greed to ease the soul and comfort the heart.

It is a mercy for it contains the sound faith, the proof to the truth and being firm on it, desire for goodness and righteous deeds, and paving the way to Allah's Pleasure and entering Paradise.

All these for the believers in the Qur'an who follow its guidance and who make it a constitution for them to which they resort in arbitration.

As for disbelievers, the Qur'an is not a cure or mercy to them as they disbelieve in its status and belie the Prophet, therefore their error, oppression, and corruption increase as a result for being away from it and going against its ruling, thus they are losers.