One day, the Imam was in the gathering of Caliph Mansur. At that time a physician was reading from a book of medicine. After he finished he addressed the Imam, “Even you are in need of this knowledge.” Imam said, “We are not in need of it. What we know is much better than what you know.” “How?” asked he.
Imam said, “We cure the diseases caused by cold, through hot medicines and diseases of heat, through cold medicines. In the same way we cure diseases of dryness, by wet medicines and diseases of wetness by dry medicines. Then in all those matters we have absolute confidence in the Almighty God. Apart from this we act upon the divine command that avoidance of harmful things is the actual cure. It is a must for everyone to observe the diet he is accustomed to.”
Hearing these statements of the Imam, the Physician said, “You are right, this is actual science of medicine.” Then he asked, “What is your opinion regarding the sneeze?” Imam replied, “Though apparently it comes out through the nose, actually it comes out from all over the body. Have you not observed that the whole body shakes during a sneeze? Remember! The person who sneezes, is assured of health for seven days.”
The Physician asked, “What do you say about rice?”
“It widens the intestines and it is beneficial in piles,” replied the Imam.
“What is your opinion about grapes and raisins?”
“They strengthen the muscles of the body, maintain the strength in the eyes, and the heart remains healthy.”
“What things are harmful to the body?”
“Firstly, dry and smelly meat, secondly, taking a bath on a full stomach. Thirdly, copulating with an aged woman. Sometimes, these even cause the death of man.”
“Please inform us about some cure.”
“Wash the hands thoroughly after eating and rub them over the eyes.”
Reference :Akhlaq al-A’imma, Morals & Manners of the Holy Imams