Two purposes of sending down Book

اعوذ بالله من الشيطن الرجيم

Surah 38. Sad, Verse 29:

كِتَابٌ أَنزَلْنَاهُ إِلَيْكَ مُبَارَكٌ لِّيَدَّبَّرُوا آيَاتِهِ وَلِيَتَذَكَّرَ أُولُو الْأَلْبَابِ

Translation:

(It is) a Book We have revealed to you abounding in good that they may ponder over its verses, and that those endowed with understanding may be mindful.

Signs of True Believers and their rewards

اعوذ بالله من الشيطن الرجيم

Surah 8. Al-Anfal, Verse 2:

إِنَّمَا الْمُؤْمِنُونَ الَّذِينَ إِذَا ذُكِرَ اللَّهُ وَجِلَتْ قُلُوبُهُمْ وَإِذَا تُلِيَتْ عَلَيْهِمْ آيَاتُهُ زَادَتْهُمْ إِيمَانًا وَعَلَىٰ رَبِّهِمْ يَتَوَكَّلُونَ

Translation:

The believers are only those who, when Allah is mentioned, feel a fear in their hearts and when His Verses (this Quran) are recited unto them, they (i.e. the Verses) increase their Faith; and they put their trust in their Lord (Alone);

Surah 8. Al-Anfal, Verse 3:

الَّذِينَ يُقِيمُونَ الصَّلَاةَ وَمِمَّا رَزَقْنَاهُمْ يُنفِقُونَ

Translation:

Who perform As-Salat (Iqamat-as-Salat) and spend out of that We have provided them.

Surah 8. Al-Anfal, Verse 4:

أُولَٰئِكَ هُمُ الْمُؤْمِنُونَ حَقًّا لَّهُمْ دَرَجَاتٌ عِندَ رَبِّهِمْ وَمَغْفِرَةٌ وَرِزْقٌ كَرِيمٌ

Translation:

It is they who are the believers in truth. For them are grades of dignity with their Lord, and Forgiveness and a generous provision (Paradise).