the believers are those whose hearts tremble when god is mentioned and when his revelations are recited to them they strengthen them in faith and upon their lord they rely.
إنما المؤمنون الذين إذا ذكر الله وجلت قلوبهم وإذا تليت عليهم آياته زادتهم إيمانا وعلى ربهم يتوكلون