The Family Of Imran - 3:151
We will strike fear into the hearts of the disbelievers because they associate with Allah those who have no power or authority. Their abode is the Fire. How evil is the abode of the wrongdoers!
Allah strikes fear into the hearts of the disbelievers through war and thus through His believing servants:
The Spoils of War/8:12
"Your Lord revealed to the angels (and therefore to the believers): "I am with you, support those who believe. I will strike fear into the hearts of the disbelievers, strike their necks, strike every finger of their hands."
The Banishment/59:2
It is He Who brought out the disbelievers from the people of the Book for the first exile. You never expected them to come out. They thought that their fortresses would protect them from Allah. But Allah came to them from a place they did not expect and struck fear in their hearts. So they destroy their houses with their own hands and the hands of the believers. O people of vision, take an example.
The Banishment/59:12
Indeed, if they are driven out, they will not go out with them. If they are fought against, they will not support them. Even if they support them, they turn their backs and flee, then they will not be helped.
The Banishment/59:13
You put fear in their hearts more than Allah. For they are a people without understanding.