Surah Ad-Dukhan, verse 1

وَٱلْكِتَـٰبِ ٱلْمُبِينِ ﴿٢﴾

By the clear Book,

إِنَّآ أَنزَلْنَـٰهُ فِى لَيْلَةٍۢ مُّبَـٰرَكَةٍ ۚ إِنَّا كُنَّا مُنذِرِينَ ﴿٣﴾

Indeed, We sent it down during a blessed night. Indeed, We were to warn [mankind].