The Holy Qur'an:
Chapter 97: Power (Qadr)

In the name of God, Most Gracious, Most Merciful

97:1. We have indeed revealed this (Message) in the Night of Power:

97:2. And what will explain to thee what the night of power is?

97:3. The Night of Power is better than a thousand months.

97:4. Therein come down the angels and the Spirit by God's permission, on every errand:

97:5. Peace!...This until the rise of morn!