إِنَّا أَنزَلْنَاهُ فِي لَيْلَةِ ٱلْقَدْرِ
Lo! We revealed it, that is, the Qur’ān, in its entirety, [sending it down] from the Preserved Tablet to the heaven of this world, on the Night of Ordainment, that is, [the Night] of great eminence.

وَمَآ أَدْرَاكَ مَا لَيْلَةُ ٱلْقَدْرِ
And what will show you, [what] will make known to you, O Muhammad (s), what the Night of Ordainment is? - [intended] to emphasise its great status and to provoke marvel at it.

لَيْلَةُ ٱلْقَدْرِ خَيْرٌ مِّنْ أَلْفِ شَهْرٍ
The Night of Ordainment is better than a thousand months, in which there is no Night of Ordainment, for a righteous deed on that Night is better than one [performed] for a thousand months without it.

تَنَزَّلُ ٱلْمَلاَئِكَةُ وَٱلرُّوحُ فِيهَا بِإِذْنِ رَبِّهِم مِّن كُلِّ أَمْرٍ
The angels and the Spirit, namely, Gabriel, descend in it, on that night, by the leave of their Lord, by His command, with every command, that God has decreed from that year to the following one.

سَلاَمٌ هِيَ حَتَّىٰ مَطْلَعِ ٱلْفَجْرِ
It is peaceful until the rising of the dawn, until the time it rises: it is peaceful because of the numerous salutations [of peace] (salām) spoken in it by the angels, who, every time they come across a believing man or believing woman, bid him peace.
Surah al-Qadr, Tafsir al-Jalalain