Abu Ja`far Ar-Razi said that Al-`Ala' bin Al-Musayyib bin Rafi` narrated from Abu Ishaq that Abu Al-Ahwas said that `Abdullah said, "Iman is to trust.''. `Ali bin Abi Talhah reported that Ibn `Abbas said,

﴿يُؤْمِنُونَ﴾

(who have faith) means they trust. Also, Ma`mar said that Az-Zuhri said, "Iman is the deeds.'' In addition, Abu Ja`far Ar-Razi said that Ar-Rabi` bin Anas said that, `They have faith', means, they fear (Allah).

Ibn Jarir (At-Tabari) commented, "The prefered view is that they be described as having faith in the Unseen by the tongue, deed and creed. In this case, fear of Allah is included in the general meaning of Iman, which necessitates following deeds of the tongue by implementation. Hence, Iman is a general term that includes affirming and believing in Allah, His Books and His Messengers, and realizing this affirmation through adhering to the implications of what the tongue utters and affirms.''

Linguistically, in the absolute sense, Iman merely means trust, and it is used to mean that sometimes in the Qur'an, for instance, Allah the Exalted said,

﴿يُؤْمِنُ بِاللَّهِ وَيُؤْمِنُ لِلْمُؤْمِنِينَ﴾

(He trusts (yu'minu) in Allah, and trusts (yu'minu) in the believers.) (9: 61)

Prophet Yusuf's brothers said to their father,

﴿وَمَآ أَنتَ بِمُؤْمِنٍ لَّنَا وَلَوْ كُنَّا صَـدِقِينَ﴾

(But you will never believe us even when we speak the truth) (12:17).

Further, the word Iman is sometimes mentioned along with deeds, such as Allah said,

﴿إِلاَّ الَّذِينَ ءَامَنُواْ وَعَمِلُواْ الصَّـلِحَـتِ﴾

(Save those who believe (in Islamic Monotheism) and do righteous deeds) (95:6).

However, when Iman is used in an unrestricted manner, it includes beliefs, deeds, and statements of the tongue.We should state here that Iman increases and decreases.

There are many narrations and Hadiths on this subject, and we discussed them in the beginning of our explanation of Sahih Al-Bukhari, all favors are from Allah. Some scholars explained that Iman means Khashyah (fear of Allah). For instance, Allah said;

﴿إِنَّ الَّذِينَ يَخْشَوْنَ رَبَّهُم بِالْغَيْبِ﴾

(Verily, those who fear their Lord unseen (i.e. they do not see Him, nor His punishment in the Hereafter)) (67:12), and,

﴿مَّنْ خَشِىَ الرَّحْمَـنَ بِالْغَيْبِ وَجَآءَ بِقَلْبٍ مُّنِيبٍ ﴾

(Who feared the Most Gracious (Allah) in the Ghayb (unseen) and brought a heart turned in repentance (to Him and absolutely free from every kind of polytheism)) (50: 33).

Fear is the core of Iman and knowledge, just as Allah the Exalted said,

﴿إِنَّمَا يَخْشَى اللَّهَ مِنْ عِبَادِهِ الْعُلَمَاءُ﴾

(It is only those who have knowledge among His servants that fear Allah) (35:28).