Hazrat Abu Saeed Khudri (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: Hearts are of four types: the Ajrad heart, meaning an empty heart in which a lamp can be lit; the Aghlaf heart, meaning a heart covered with veils; the Mankus heart, meaning an inverted heart; and the Musfah heart, meaning a barren plain. The Ajrad heart is the heart of a Muslim, whose lamp is its light. The Aghlaf heart is the heart of a disbeliever. The Mankus heart is the heart of a hypocrite, who, after recognizing the truth, denies it. The Musfah heart is the heart in which there is both faith and hypocrisy. The example of faith in it is like greenery that grows with good and pure water, and the example of hypocrisy is like a wound in which pus and blood increase. Now, whichever of the two becomes dominant, its effect prevails over it.