Musannaf Ibn Abi Shaybah 32423 — Book of Faith

Abu al-Bakhtari (may Allah have mercy on him) said that Sayyiduna Hudhayfah (may Allah be pleased with him) said: Hearts are of four kinds. One is a heart in which there is adulteration: this is the heart of the hypocrite. One is a heart wrapped in a covering: this is the heart of the disbeliever. One is a heart that is clear, with light shining from it: this is the heart of the believer. And one is a heart in which there is both hypocrisy and faith. Its likeness is that of a boil containing pus and blood, and its likeness is that of a tree that receives both clean and foul water: whichever water prevails, its effect is what appears in it.