Translation:

5. It is a Revelation sent down by (Him) the Exalted in Might Most Merciful.

Notes (Tafseer)

3945. The Revelation again is characterised by two attributes which we find most helpful in contemplating about Allah. It has force and power: for Allah is Exalted in Might and able to enforce His Will. And it brings a Message of hope and mercy; for Allah is Most Merciful. By its characteristics we know that the Qur-an is from Allah.