2. 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);
3. Who perform As-Salat (Iqamat-as-Salat) and spend out of that We have provided them.
4. 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).
Quran (Surah Al-Anfal, verses 2 – 4)
It’s clear from these verses that the qualities of a true Muslim mentioned in these verses are the following:
When Allah is mentioned, they feel the fear of Him in their hearts;
Their faith increases every time they hear and ponder over Quran’s verses;
They put their trust in Allah, i.e. have Tawakkul on Allah;
They perform prayers regularly;
They spend in charity in the path of Allah.
As a Muslim, one can take heed from these verses and assess the state of his heart. In his tafsir, Ibn Kathir writes that 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.
The primary point is that a true believer is one when Allah is mentioned, he feels a fear in his heart, and thus implements His orders and abstains from His prohibitions.
About such people, Sufyan Ath-Thawri narrated that As-Suddi commented, “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.”
Finally, for such people Allah has promised ‘grades of dignity’, i.e. special places in paradise. We know from various ahadith that paradise has many levels and the more deserving are granted better and higher grades in paradise. In a Hadith recorded by Imam Ahmad and the collectors of Sunan, Abu Atiyyah said that Ibn Abu Said said that the Messenger of Allah said,
“Residents of Paradise see the residents of the highest grades just as you see the distant planet in the horizon of the sky. Verily, Abu Bakr and `Umar are among them (in the highest grades), and how excellent they are.”
Reference: Quran and Tafsir Ibn Kathir