What is the authenticity of the hadith: "Whoever drinks harmal for forty mornings, a mithqal each day, for the illumination of wisdom in his heart, will be cured of seventy-two diseases, the least of which is leprosy?"

There is no authentic hadith stating that harmal (Peganum harmala) bestows wisdom. Wisdom is acquired through deep understanding of the religion (fiqh), piety, and righteous deeds. As for what has been reported regarding harmal being a cure for seventy-two diseases, its chain of transmission (isnad) is weak and it is exaggerated, not resembling the authentic hadith of the Prophet, peace and blessings be upon him.