Purification of the Heart: Diseases of the Heart in Islamic Teaching

A look at purification of the heart in Islamic teaching, drawn from the Quran and authentic hadith.

Islamic teaching locates the real measure of a person’s standing before Allah not in outward ritual alone, but in the condition of a single organ: the qalb, the heart. A hadith recorded in Sahih Muslim has the Prophet Muhammad ﷺ pointing to his own chest three times while saying, “Taqwa is here,” making the heart, not visible piety, the actual site where a person’s religion is judged.

Purification of the heart: The Verse That Frames the Entire Discussion

Surah ash-Shu’ara describes the Day of Judgment as a day “when neither wealth nor children will be of benefit, except one who comes to Allah with a sound heart” (26:88-89) – a qalbin saleem, a heart free of corruption. Classical exegetes treat this verse as the organizing principle behind an entire branch of Islamic scholarship devoted to the heart’s spiritual health, since it makes the heart’s condition, rather than wealth, lineage, or even offspring, the single asset that carries any weight in the final reckoning.

The Piece of Flesh That Corrupts the Whole Body

A hadith recorded in Sahih al-Bukhari and Sahih Muslim, narrated by Nu’man ibn Bashir, describes the Prophet ﷺ teaching that the body contains a small piece of flesh which, if sound, makes the whole body sound, and if corrupted, corrupts the whole body – and that this piece of flesh is the heart. Classical scholars, most extensively Imam al-Ghazali in the sections of his “Ihya Ulum al-Din” devoted to the heart, and Ibn Qayyim al-Jawziyyah in his “Ighathat al-Lahfan,” built on this hadith to argue that outward good deeds performed without inward correction eventually decay, since the heart is what genuinely drives behavior over time, not the reverse.

The Black Dot: How Sin Accumulates Unnoticed

A hadith recorded by al-Tirmidhi describes sin leaving a black mark on the heart each time it is committed, one dot at a time, until – if the person does not turn back to Allah in repentance – the heart becomes entirely covered over, described in the hadith using the Quranic term “rayn,” a sealing over mentioned in Surah al-Mutaffifin (83:14): “Nay, but that which they used to earn has rusted upon their hearts.” This image of gradual, cumulative buildup rather than sudden corruption is central to how classical scholars explain why small, seemingly minor sins are treated with real seriousness in Islamic ethics – not because any single one is catastrophic, but because of what steady repetition does to the heart’s capacity to feel anything at all.

Diseases Scholars Named: Kibr, Hasad, and Riya

Classical scholarship on the heart, particularly al-Ghazali’s writing, identifies specific spiritual diseases by name, treating each as something to be diagnosed and actively treated rather than passively regretted. Kibr, arrogance, is addressed in a hadith recorded in Sahih Muslim in which the Prophet ﷺ defines it precisely as “rejecting the truth and looking down on people” – a definition scholars point to as proof that arrogance is fundamentally a disease of judgment toward others, not merely a personality trait. Hasad, envy, resenting a blessing given to someone else and wishing it removed, is addressed in a hadith in Sunan Abu Dawud warning that it “consumes good deeds as fire consumes firewood.” Riya, showing off in worship – performing an act of devotion to be seen and praised by others rather than sincerely for Allah – is termed “the lesser shirk” in a hadith recorded by Imam Ahmad, a description scholars have treated as unusually severe given that shirk is otherwise the gravest category of sin in Islamic theology.

Dhikr as the Prescribed Treatment

Against this backdrop of accumulating spiritual disease, the Quran offers a specific remedy: “Verily, in the remembrance of Allah do hearts find rest” (Surah ar-Ra’d, 13:28). Classical scholars treat dhikr – the regular repetition of Allah’s names and short formulas of praise and remembrance – not as a devotional add-on but as the direct treatment for the black-dot accumulation described in the hadith literature, on the reasoning that if sin marks the heart one act at a time, remembrance and repentance work to clean it in the same incremental way, rather than through any single dramatic act of purification.

Sincere Repentance and the Heart Made New

Islamic teaching does not treat a corrupted heart as a permanent condition. A hadith recorded in Sahih Muslim describes Allah’s joy at a servant’s repentance as greater than the joy of a traveler who had given up his mount for lost in the desert, with all his food and water on it, only to find it standing beside him again. Scholars use this hadith specifically in discussions of the heart’s purification to argue that no accumulation of spiritual disease, however extensive, is treated in Islamic teaching as beyond the reach of sincere tawbah, repentance – the process by which classical scholarship holds that even a heart heavily marked can, in principle, be returned to the “qalbin saleem,” the sound heart, that Surah ash-Shu’ara describes as the only asset that matters on the Day of Judgment.

The Three States of the Heart

Ibn Qayyim al-Jawziyyah, in his writings on the states of the heart, describes three distinct conditions a heart can be found in, a framework later scholars have continued to draw on when diagnosing their own spiritual condition. The first is al-qalb as-saleem, the sound heart, free of corruption and turned entirely toward Allah, the standard described in Surah ash-Shu’ara. The second is al-qalb al-mayyit, the dead heart, one that no longer recognizes its Lord, feels no pull toward obedience, and takes no discomfort from sin – a condition scholars describe as the most dangerous precisely because the person in it typically feels no urgency to change. Between these two lies al-qalb al-maridh, the sick heart, containing genuine faith and love of Allah alongside real disease – desire, heedlessness, or attachment to sin – locked in an ongoing internal struggle between the two. Scholars describe this third category as the condition of the overwhelming majority of believers at any given time, and treat dhikr, sincere repentance, and the deliberate avoidance of the specific diseases named above as the means by which a sick heart is nursed back toward soundness rather than allowed to drift toward death.

Taken together, these points are why purification of the heart continues to shape how practicing Muslims think and act today.

This discussion pairs naturally with our article on The Etiquette of Eating and Drinking in Islam. For further primary-source reading, Sunnah.com offers searchable access to the full text of the Quran and its major hadith collections.