A description of what belief does physically
Three signs listed, and the first is involuntary.
إِنَّمَا ٱلْمُؤْمِنُونَ ٱلَّذِينَ إِذَا ذُكِرَ ٱللَّهُ وَجِلَتْ قُلُوبُهُمْ وَإِذَا تُلِيَتْ عَلَيْهِمْ ءَايَـٰتُهُۥ زَادَتْهُمْ إِيمَـٰنًا وَعَلَىٰ رَبِّهِمْ يَتَوَكَّلُونَ
Innama-l-mu'minūna-lladhīna idhā dhukira-llāhu wajilat qulūbuhum wa idhā tuliyat ʿalayhim āyātuhu zādathum īmānā…
“The believers are only those who, when Allāh is mentioned, their hearts become fearful, and when His verses are recited to them, it increases them in faith; and upon their Lord they rely -”
Source
The Qur'an · 8:2
Qur'an
- Qur'anic text in the Uthmani script via Quran.com; translation: Saheeh International