Qualities of the Faithful and Truthful Believers
Allah says;
إِنَّمَا الْمُوْمِنُونَ الَّذِينَ إِذَا ذُكِرَ اللّهُ وَجِلَتْ قُلُوبُهُمْ وَإِذَا تُلِيَتْ عَلَيْهِمْ ايَاتُهُ زَادَتْهُمْ إِيمَانًا وَعَلَى رَبِّهِمْ يَتَوَكَّلُونَ
The believers are only those who, when Allah is mentioned, feel a fear in their hearts and when His Ayat are recited unto them, they increase their faith; and they put their trust in their Lord;
Ali bin Abi Talhah reported that Ibn Abbas said about the Ayah,
إِنَّمَا الْمُوْمِنُونَ الَّذِينَ إِذَا ذُكِرَ اللّهُ وَجِلَتْ قُلُوبُهُمْ
(The believers are only those who, when Allah is mentioned, feel a fear in their hearts),
"None of Allah's remembrance enters the hearts of the hypocrites upon performing what He has ordained. They neither believe in any of Allah's Ayat nor trust (in Allah) nor pray if they are alone nor pay the Zakah due on their wealth. Allah stated that they are not believers. He then described the believers by saying,
إِنَّمَا الْمُوْمِنُونَ الَّذِينَ إِذَا ذُكِرَ اللّهُ وَجِلَتْ قُلُوبُهُمْ
(The believers are only those who, when Allah is mentioned, feel a fear in their hearts) and they perform what He has ordained,
وَإِذَا تُلِيَتْ عَلَيْهِمْ ايَاتُهُ زَادَتْهُمْ إِيمَانًا
(and when His Ayat are recited unto them, they increase their faith) and conviction,
وَعَلَى رَبِّهِمْ يَتَوَكَّلُونَ
(and they put their trust in their Lord), having hope in none except Him."
Mujahid commented on,
وَجِلَتْ قُلُوبُهُمْ
(their hearts Wajilat),
"Their hearts become afraid and fearful."
Similar was said by As-Suddi and several others.
The quality of a true believer is that when Allah is mentioned, he feels a fear in his heart, and thus implements His orders and abstains from His prohibitions.
Allah said in a similar Ayah,
وَالَّذِينَ إِذَا فَعَلُواْ فَـحِشَةً أَوْ ظَلَمُواْ أَنْفُسَهُمْ ذَكَرُواْ اللَّهَ فَاسْتَغْفَرُواْ لِذُنُوبِهِمْ وَمَن يَغْفِرُ الذُّنُوبَ إِلاَّ اللَّهُ وَلَمْ يُصِرُّواْ عَلَى مَا فَعَلُواْ وَهُمْ يَعْلَمُونَ
And those who, when they have committed Fahishah (immoral sin) or wronged themselves with evil, remember Allah and ask forgiveness for their sins; -- and none can forgive sins but Allah -- and do not persist in what (wrong) they have done, while they know. (3:135)
and,
وَأَمَّا مَنْ خَافَ مَقَامَ رَبِّهِ وَنَهَى النَّفْسَ عَنِ الْهَوَى
فَإِنَّ الْجَنَّةَ هِىَ الْمَأْوَى
But as for him who feared standing before his Lord, and restrained himself from vain desires. Verily, Paradise will be his abode. (79:40-41)
Sufyan Ath-Thawri narrated that As-Suddi commented,
إِنَّمَا الْمُوْمِنُونَ الَّذِينَ إِذَا ذُكِرَ اللّهُ وَجِلَتْ قُلُوبُهُمْ
(The believers are only those who, when Allah is mentioned, feel a fear in their hearts),
"A man might be thinking of committing injustice or a sin. But he abstains when he is told, `Have Taqwa of Allah', and his heart becomes fearful."'
Faith increases when the Qur'an is recited
Allah's statement,
...
وَإِذَا تُلِيَتْ عَلَيْهِمْ ايَاتُهُ زَادَتْهُمْ إِيمَانًا
...
And when His Ayat are recited unto them, they increase their faith;
is similar to His statement,
وَإِذَا مَأ أُنزِلَتْ سُورَةٌ فَمِنْهُمْ مَّن يَقُولُ أَيُّكُمْ زَادَتْهُ هَـذِهِ إِيمَـناً فَأَمَّا الَّذِينَ ءامَنُواْ فَزَادَتْهُمْ إِيمَـناً وَهُمْ يَسْتَبْشِرُونَ
And whenever there comes down a Surah, some of them (hypocrites) say: "Which of you has had his faith increased by it!" As for those who believe, it has increased their faith, and they rejoice. (9:124)
Al-Bukhari and other scholars relied on this Ayah (8:2) and those similar, as evidence that faith increases and varies in strength from heart to heart.
This is also the view of the majority of the scholars of Islam, prompting some scholars, such as Ash-Shafi`i, Ahmad bin Hanbal and Abu Ubayd to declare that this is the consensus of the Ummah, as we mentioned in the beginning of the explanation of Sahih Al-Bukhari. All the thanks and praises are due to Allah.
The Reality of Tawakkul
Allah said,
...
وَعَلَى رَبِّهِمْ يَتَوَكَّلُونَ
And they put their trust in their Lord.
Therefore, the believers hope in none except Allah, direct their dedication to Him alone, seek refuge with Him alone, invoke Him alone for their various needs and supplicate to Him alone. They know that whatever He wills, occurs and that whatever He does not will never occurs, that He alone is the One Who has the decision in His kingdom, without partners; none can avert the decision of Allah and He is swift in reckoning.
Hence the statement of Sa`id bin Jubayr,
"Tawakkul of Allah is the essence of faith.
Deeds of Faithful Believers
Allah said next,
الَّذِينَ يُقِيمُونَ الصَّلَةَ وَمِمَّا رَزَقْنَاهُمْ يُنفِقُونَ
