Abu Sa’eed reported: The Messenger of Allah, ‎ﷺ‎‬, said:

الْقُلُوبُ أَرْبَعَةٌ 

The hearts are four kinds: 

قَلْبٌ أَجْرَدُ فِيهِ مِثْلُ السِّرَاجِ يُزْهِرُ

a polished heart as shiny as a radiant lamp,

وَقَلْبٌ أَغْلَفُ مَرْبُوطٌ عَلَى غِلَافِهِ

 a sealed heart with a knot tied around it,

وَقَلْبٌ مَنْكُوسٌ

 a heart that is turned upside down, 

وَقَلْبٌ مُصْفَحٌ

and a heart that is wrapped. 

فَأَمَّا الْقَلْبُ الْأَجْرَدُ فَقَلْبُ الْمُؤْمِنِ سِرَاجُهُ فِيهِ نُورُهُ

As for the polished heart, it is the heart of the believer and its lamp is the light of faith. 

وَأَمَّا الْقَلْبُ الْأَغْلَفُ فَقَلْبُ الْكَافِرِ

The sealed heart is the heart of the unbeliever. 

وَأَمَّا الْقَلْبُ الْمَنْكُوسُ فَقَلْبُ الْمُنَافِقِ عَرَفَ ثُمَّ أَنْكَرَ

The heart that is turned upside down is the heart of a pure hypocrite, for he had knowledge but he denied it. 

 وَأَمَّا الْقَلْبُ الْمُصْفَحُ فَقَلْبٌ فِيهِ إِيمَانٌ وَنِفَاقٌ 

As for the heart that is wrapped, it is the heart that contains both faith and hypocrisy. 

فَمَثَلُ الْإِيمَانِ فِيهِ كَمَثَلِ الْبَقْلَةِ يَمُدُّهَا الْمَاءُ الطَّيِّبُ 

The parable of faith in this heart is the parable of the herb that is sustained by pure water, 

وَمَثَلُ النِّفَاقِ فِيهِكَمَثَلِ الْقُرْحَةِ يَمُدُّهَا الْقَيْحُ وَالدَّمُ

and the parable of the hypocrisy in it is the parable of an ulcer that thrives upon puss and blood; 

  فَأَيُّ الْمَدَّتَيْنِ غَلَبَتْ عَلَى الْأُخْرَى غَلَبَتْ عَلَيْهِ

whichever of the two is greater will dominate.

Source: Musnad Ahmad 10745, Grade: Sahih