﴿ إِنَّمَا ٱلْمُؤْمِنُونَ ٱلَّذِينَ إِذَا ذُكِرَ ٱللَّهُ وَجِلَتْ قُلُوبُهُمْ وَإِذَا تُلِيَتْ عَلَيْهِمْ ءَايَٰتُهُۥ زَادَتْهُمْ إِيمَٰنًۭا وَعَلَىٰ رَبِّهِمْ يَتَوَكَّلُونَ ﴾

“Believers are only they whose hearts tremble with awe whenever God is mentioned, and whose faith is strengthened whenever His messages are conveyed unto them, and who in their Sustainer place their trust -”

The believers are those whose hearts tremble [with awe], when God is mentioned�He [Sahl] said:Their [hearts] tremble from the fear of separation (firāq), and hence their bodily members humbly submit to God in [His] service (khidma).His words, Exalted is He: