Surah Al-Qadr, ayah 1

إِنَّآ أَنزَلۡنَٰهُ فِي لَيۡلَةِ ٱلۡقَدۡرِ ١

Innā anzalnāhu fī laylatil-qadr

Indeed, We sent it [i.e., the Qur’ān] down during the Night of Decree.