[3:151] We will cast terror into the hearts of the disbelievers; for what they have associated with God that for which He has revealed no warrant; their abode shall be the Fire; evil is the abode of the evildoers.
God (s) designated our Prophet (ṣ) to cast terror (ruʿb) from Him into the hearts of His enemies. [The Prophet] (ʿa) said: I was helped by terror (ruʿb). He also follows this way (sunna) with His friends. He puts fear (hayba) of them in hearts. Fear (hayba) and force (qahr) would hardly be right in hearts were it not from Him and used with those who follow falsehood, make false claims, and misrepresent.