The heart of a believer is illuminated…

Sayyiduna Abu Sa’id radiAllahu anhu narrates: The Messenger of Allah ﷺ said:

الْقُلُوبُ أَرْبَعَةٌ قَلْبٌ أَجْرَدُ فِيهِ مِثْلُ السِّرَاجِ يُزْهِرُ وَقَلْبٌ أَغْلَفُ مَرْبُوطٌ عَلَى غِلَافِهِ وَقَلْبٌ مَنْكُوسٌ وَقَلْبٌ مُصْفَحٌ فَأَمَّا الْقَلْبُ الْأَجْرَدُ فَقَلْبُ الْمُؤْمِنِ سِرَاجُهُ فِيهِ نُورُهُ وَأَمَّا الْقَلْبُ الْأَغْلَفُ فَقَلْبُ الْكَافِرِ وَأَمَّا الْقَلْبُ الْمَنْكُوسُ فَقَلْبُ الْمُنَافِقِ عَرَفَ ثُمَّ أَنْكَرَ وَأَمَّا الْقَلْبُ الْمُصْفَحُ فَقَلْبٌ فِيهِ إِيمَانٌ وَنِفَاقٌ فَمَثَلُ الْإِيمَانِ فِيهِ كَمَثَلِ الْبَقْلَةِ يَمُدُّهَا الْمَاءُ الطَّيِّبُ وَمَثَلُ النِّفَاقِ فِيهِ كَمَثَلِ الْقُرْحَةِ يَمُدُّهَا الْقَيْحُ وَالدَّمُ فَأَيُّ الْمَدَّتَيْنِ غَلَبَتْ عَلَى الْأُخْرَى غَلَبَتْ عَلَيْهِ

There are four kinds of hearts: a polished heart as illuminated as a radiant lamp, a heart which is sealed with a knot tied around it, a heart that is turned upside down, and a heart that is wrapped.

As for the heart that is polished, it is the heart of the believer and its lamp is the light of faith. The sealed heart is the heart of the unbeliever. The heart that is turned upside down is the heart of a pure hypocrite, for he had knowledge but he denied it. As for the heart that is wrapped, it is the heart that contains both faith and hypocrisy.

The parable of faith in this heart is the parable of the herb that is sustained by pure water, and the parable of the hypocrisy in it is the parable of an ulcer that thrives upon puss and blood; whichever of the two is greater will dominate.

Ref: Musnad Imam Ahmad