إِنَّآ أَنزَلْنَـٰهُ فِى لَيْلَةٍ مُّبَـٰرَكَةٍ ۚ إِنَّا كُنَّا مُنذِرِينَ

The total clarity of the Quran is in itself proof of its being the Book of God, and this being so, its tidings and forecasts are also definitive. There is no scope for any doubt about them. The beginning of the revelation of the Quran took place on a particular night—a night fixed for important godly decisions. The revelation of the Quran was not a simple event. It resulted from a decision regarding the dawn of a new era of history. That is why it was revealed on this specially blessed night. Primarily, the Quran was and still is a declaration of Truth. It came into existence in order to show the falsity of polytheism and the truth of the Unity of God. Most importantly, it provides man with a standard by which to distinguish between truth and falsehood. The Quran was the distinguisher among nations solely on this basis.

— Source: Tazkirul Quran (Maulana Wahiduddin Khan) via Quran.com (44:3)