Bismillah, alhamdulillah wa-salaatu wa-salaamu 'ala Rasulullah
Imam Ahmad recorded Abu Sa`id, radiallahu 'anhumma, reporting that the Messenger of Allah salallahu 'alayhi wa salaam said:
"The hearts are of four types: Polished and shiny as a radiating lamp. A sealed heart with a knot tied around it. A heart that is turned upside down and a wrapped heart.
As for the polished heart, it is the heart of the believer and its lamp is the light of faith.
The sealed heart is the heart of the disbeliever.
The heart that is turned upside down is the heart of the pure hypocrite, because he contained knowledge but denied it.
As for the wrapped heart, it is a heart that contains belief and hypocrisy. The example of faith in this heart is the example of the herb that is sustained by pure water. The example of hypocrisy in it is the example of an ulcer that thrives on puss and blood. Whichever of the two substances is most dominant, will have dominance over that heart."
(This hadith has a jayid hasan isnad - classified good chain of narration)
O Allah give and maintain for us polished hearts whose light radiates from our intentions, attitudes and deeds. Grant us the determination and patience, ya Rabb, to gain success and satifaction in this world and al-Akhirah, keeping us safe from the disease of nifaq (hypocrisy) always. Allahumma ameen.
Ya Muqallibal qulubli thabbit qulbi 'ala dinika (O Turner of Hearts, turn my heart that it is firm and steadfast in Your Way)!